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14[[quoteright:350:[[Webcomic/{{Hiimdaisy}} https://static.tvtropes.org/pmwiki/pub/images/turnabout_taboo.png]]]]
15[[caption-width-right:350:[[VisualNovel/ApolloJusticeAceAttorney Why didn't he tell them that]] ''[[VisualNovel/ApolloJusticeAceAttorney before]]'' [[VisualNovel/ApolloJusticeAceAttorney they got married?]]]]
16
17->''"How was I supposed to know that we were both related?\
18Believe me, if I knew she was my cousin we never woulda dated."''
19-->-- '''Music/WeirdAlYankovic''', [[Music/PoodleHat "A Complicated Song"]]
20
21''The Game the Whole Family Can Play!''
22''Haha! Guess what you were doing?''
23
24Sometimes in stories, two people meet and just seem destined for romance. Love blossoms in a particular way, or perhaps the two have a loveless ArrangedMarriage lying in wait for them instead. But then, someone makes a startling discovery -- genetics has struck! The couple-to-be are related -- and not in the "same species" sense -- and the romance or arranged marriage is called off. The result may be either great rejoicing or great despair. If it's ''not'' called off despite the consanguinity issue, intentional BrotherSisterIncest results. Or if the two still want to be together and the author doesn't want to go the incest route, a counter-reveal may show up to prove that [[NotBloodSiblings the genetics aren't a problem after all]].
25
26These days, many people are {{squick}}ed out by this, so the characters often find out ''before'' they tie the knot/do the nasty. This wasn't always the case; Oedipus was very happily (but unknowingly) married to his own mother for many years and had two daughters with her before things fell apart (to the extent that TheReveal resulted in Oedipus' mother killing herself and Oedipus himself stabbing his own eyes out), so this is OlderThanFeudalism. Still, this trope is surprisingly common in {{anime}} and {{manga}}, as well as other Japanese entertainment, due to much more relaxed views on the subject in Japan.
27
28The surprise relationship is usually either brother/sister or half-siblings (sharing one parent rather than both). Parent/child is much rarer these days than it was in ancient Greece, and similarly for uncle/niece or aunt/nephew, thanks to some cultures' taboos on inter-generational relationships, even with no family relations involved.
29
30[[KissingCousins First cousins]], on the other hand, are only borderline {{squick}}y since marriage between cousins is actually legal in most places and is quite acceptable in many romance novels. In fact, in the ''Literature/ArabianNights'', a man will call a woman he loves or is married to "daughter of my uncle" because, at that time, marriage between cousins was considered the best option! Because of this, it almost never appears as a plot point since it's a little too close for some folks to be comfortable but not close enough that the plot demands the relationship break up. For relations more distant than first cousins (second cousins, removals and etc.), the squick diminishes with the distance. After all, thanks to how genetics and inheritance works within populations, if you're still having a problem with people who might be, say, 10th cousins or higher, the only relationship you're likely to be assuaged by is one where the couple come from radically different population groups.[[note]]To give a more concrete example: the British panel game Series/{{QI}} once made an announcement that they knew for a fact that one of the panelists that evening was a descendent of the legendary 8th century ruler Charlemagne. Who was it? One of the panelists guessed it immediately - all of them. As well as the host, and the audience, and anyone watching at home, assuming they were from Europe at any point in their family tree. And it wasn't that Charlemagne ReallyGotAround, it was just that with so many generations since his time, everyone, by dint of pure mathematics (again, if you are of a European background) had to have at least some relationship with him.[[/note]]
31
32The relationship is more like to be on the paternal side, because of MamasBabyPapasMaybe. Historically was a fairly common way of making the Veronica of a BettyAndVeronica off-limits. This often results in HalfSiblingAngst.
33
34If the characters don't know the truth in advance but the audience does, this overlaps with DramaticIrony. There's also potential for overlap with IncestantAdmirer if the admirer isn't aware of the familial relation but the object of their affection is, or if the reveal of said relation bothers one party but not the other.
35
36'''Expect spoilers.'''
37----
38!!Examples:
39
40[[foldercontrol]]
41
42[[folder:Anime & Manga]]
43* The prince and princess from ''Anime/AndromedaStories'', a pair of HalfIdenticalTwins who were SeparatedAtBirth, get into a relationship before learning of their heritage. Weirdly, they decide to stay together after the truth comes out, citing the fact that incest is fairly common in royal families.
44* While the characters never know it, ''Manga/BirdyTheMighty Decode'' sees this: [[spoiler:Nataru, the titular Birdy's love interest and childhood friend was, like her, created in lab as a SuperSoldier -- the same lab to be precise, which means there's a good chance Nataru and Birdy are brother and sister]].
45* In the time travel arc of ''Manga/{{Boruto}}'', [[ShipperOnDeck Ino]] teases 12 year old [[ShrinkingViolet Hinata]] about how she isn't shy around Boruto. Hinata is Boruto's future mother. Subverted in that Hinata isn't attracted to Boruto.
46* ''Manga/CaseClosed'' has a case [[spoiler:with Raita Banba and his fiancee, Hatsune Kamon]]. Uniquely, it turns out that [[spoiler: they're identical twins and that the latter has [[http://en.wikipedia.org/wiki/Turner_syndrome Turner syndrome]] ]]. [[spoiler: Hatsune]] suspected something was up upon learning that in addition to their identical birth dates, blood types, and unusual ability to know what the other was thinking even when they were silent, that they'd both been adopted after being orphaned as infants in a massive fire that destroyed their birth neighborhood. [[spoiler:When she gets the test results confirming it, she... [[DrivenToSuicide doesn't take it well]]. And for worse, ''[[CrazyJealousGuy Raita]] is accused of having killed her in a {{Yandere}} fit''. Conan, through Kogoro, has to clear his name.]]
47* In ''Manga/CountCain'', unbeknownst to him, the main character's mother is his father's older sister. He then proceeds to fall in love with his first cousin, which was legal in the time period. The problem is, his cousin is his father's older sister's daughter, making her also his half-sister. There are a couple of other brother/sister couples as throwaway characters, too.
48* In ''Manga/DailyLivesOfHighSchoolBoys'', Emi, after days of CannotSpitItOut, finally finds the chance to confess her love to the visiting Hidenori on a festival, which coincides with his last day in town which happened to be his maternal hometown. But just when she thinks she finally found her chance, Hidenori makes a most surprising revelation to her: they are cousins.
49-->'''Emi''': "And so, I ended my summer break without being able to do a thing."
50* ''Literature/DoYouLoveYourMomAndHerTwoHitMultiTargetAttacks'': In the BeachEpisode OVA, Masato gets hit on the head and gets amnesia. He becomes attracted to his own mother Mamako. Eventually, he declares his love for her, then grabs her and tries to kiss her. [[MomentKiller A kraken attacks them and then he suddenly regains his memories]].
51* ''Manga/DomesticGirlfriend'': A NotBloodSiblings example. Natsuo has a crush on his teacher Hina and ends up having sex with Rui, a girl he met at a mixer, in an attempt to forget about her. A week later, his father gets remarried and his new stepmother brings her daughters Hina and Rui to live with them. As his feelings for the girls grow, he keeps trying to keep himself under control by reminding himself that they are his sisters. [[spoiler:He eventually starts dating Hina, but that relationship ends because of their teacher/student relationship. Much later, he starts dating Rui, and while their relationship is much more stable, they still have to deal with the fact that they have to hide it from their parents]].
52* ''Manga/{{Doraemon}}'': Nobita's father has a brief crush on a mysterious girl he met in the past, not knowing the girl was his own son from the future in UnplannedCrossdressing. Nobita and Doraemon eventually decide not to tell him.
53* ''Anime/DragonBallZ'' has a minor example with Bulma gently hitting on Trunks well before she learns that he's her KidFromTheFuture.
54* In the first chapter of ''Manga/FamilyCompo'' Masahiko meets Shion and finds her attractive. Later that day he learns she is his cousin. The series sways between them being like siblings and them being KissingCousins, with a lean towards the latter.
55* Averted in ''Manga/FoodWars''. [[spoiler:Asahi Saiba wants to forcibly marry Erina Nakiri to become the greatest chef. He plans to defeat her at the BLUE competition, but is instead defeated by Soma Yukihira. Months later, Asahi and Erina are shocked to discover that they share the same father.]]
56* {{Subverted|Trope}} in ''Anime/FromUpOnPoppyHill.'' Uma and Shun spend the first third of the movie growing close, until Shun sees a picture of her dad and realizes it's the same man whom he believes to be his biological father. Ultimately, they discover that his father was a friend of Uma's, and that he only took care of him temporarily as a baby.
57* ''Franchise/{{Gundam}}'':
58** Depending on your interpretation of their relationship before the big reveal, Kira and Cagalli of ''Anime/MobileSuitGundamSEED''. They never really got around to doing anything, but they definitely looked like the usual romantic pairing all the way up to the last five episodes of the series. Especially since the first half of ''Gundam SEED'' was heavily based on the original ''Anime/MobileSuitGundam'', with Kira and Cagalli having roles roughly analogous to Amuro and Sayla. WordOfGod is that this was a deliberate reference to Luke and Leia.
59** Bellri has a crush on Aida throughout the first half of Anime/GundamReconguistaInG. Fortunately, Aida keeps him at arm's length for various reasons(such as accidentally killing her mentor), so it hasn't gotten anywhere by the time they find out they're siblings, so it's quickly dropped.
60* Subverted in ''I Know All About It''. The main character receives a visit from her younger sister, who confesses to being the woman who had sex with the main character the previous night. The main character then says that she knew about her younger sister's feelings for her, and that she went along with it because she reciprocated those feelings.
61* In ''Anime/JewelpetSunshine'', Kanon and Mikage start dating around mid-series; towards the end of the show, Kanon's adoptive-all-along mother reveals to her that she and Mikage are actually twin siblings, who had to be separated because of a misinterpreted prophecy.
62* ''Manga/JoJosBizarreAdventure'':
63** ''[[Manga/JoJosBizarreAdventureBattleTendency Battle Tendency]]'': A (thankfully) {{downplayed|Trope}} example happens when [[spoiler:Joseph]] unknowingly [[ThePeepingTom peeps]] on his mother, [[spoiler:Lisa Lisa]].
64** ''[[Manga/JoJosBizarreAdventureStoneOcean Stone Ocean]]'': A [[SwitchedAtBirth baby switch]] eventually led to Perla Pucci dating her older brother Wes Bluemarine, [[spoiler:a.k.a. Weather Report]]. Enrico, upon discovering the relation, tried to keep the damage to a minimum by not telling her and instead hiring a third party to make them break up. Too bad the third party's method of doing this was to lynch Wes.
65* ''Manga/KoiKaze'' has 27-year-old Koshiro and 15-year-old Nanoka having a [[MeetCute chance encounter]], going to an amusement park together, forming an emotional connection and spark of mutual attraction, and then finding out they're brother and sister in ''the first episode''. This turns into a deconstruction of BrotherSisterIncest, as the two struggle to resist their mutual attraction while living in the same house but eventually go on to develop a painful and guilt-ridden romantic relationship against their better judgment, fully aware of the devastating implications if their secret got out, but both unwilling to live without the other.
66* In one of ''Manga/TheLegendOfZeldaI'' manga, an adaptation of ''VideoGame/TheLegendOfZeldaI'', Link has a crush on Princess Zelda. Unknown to him, he is her older half-brother who was abandoned because he was half-elf and the previous Zelda didn't want her husband killing him. The manga never shows him learning that they're related. Zelda knows they're related, and doesn't requite Link's feelings, but is never shown telling him that they're related.
67* A possible example is [[spoiler:Millernium "Milly" Feria Noctum and Kane Blueriver]] in ''Literature/LostUniverse'', although, since they are second-cousins, they're probably distant enough to date if they really wanted to, and the ''very'' open ending lends serious doubts as to whether [[spoiler: Kane survives the end of the series]] anyway.
68* In ''Manga/MarmaladeBoy'', Yu and Miki discovers that both their parents have known each other from before their divorce and remarriage, where they are paired together the same way as their current set-up. This causes Yuu to suspect that he and Miki are half-siblings, but their parents reassure them that they are not.
69* ''Manga/MayasFuneralProcession'' has the main character, Reina, falling in love with [[spoiler:a mysterious girl named Maya]], only to discover that [[spoiler:Reina is the product of her mother's affair with Maya's father]] and thus they're actually half-siblings.
70* Negi and [[spoiler:Asuna]], one of the most popular and [[ShipTease teased]] pairings in ''Manga/NegimaMagisterNegiMagi'', [[spoiler: are ''very'' distantly related by the Lifemaker, maybe closer, but how close was never specified]].
71* In ''Anime/NeonGenesisEvangelion,'' [[ClassicalAntiHero Shinji]] and [[spoiler:the second]] [[EmotionlessGirl Rei]] become friends, with a definite undercurrent of romantic attraction. One of several disturbing revelations in the latter half of the series is that Rei is actually [[spoiler:a clone of Shinji's dead mom]].
72* Kanba and Masako subvert this in ''Anime/{{Penguindrum}}''. They know about their bond and have it more or less clear (though Masako has quite the case of BigBrotherAttraction as shown when she ''kisses'' Kanba), but it's a surprise to the ''audience'' and to Kanba's adoptive sister Himari. Doubles as {{Twincest}}.
73* ''Anime/PleaseTwins'' played with this one. Each girl came believing that she was the twin sister. They find out about each other and realize that they each have a 50/50 chance of being the twin. They both fall in love with the man a few episodes ''after'' this. The irony being the anime had one of the girls be the guy's sister, and the {{novelization}} had the other one.
74* In ''Manga/{{Saiyuki}}'', fraternal twins Cho Gonou and Cho Kanan were separated at a very young age when their parents divorced, one parent taking each child. Years later, they met at school, fell in love, discovered their relationship to one another, and became lovers, in that order.
75* ''Anime/SailorMoon'':
76** Shingo Tsukino has a huge crush on Sailor Moon, as he's unaware that she is actually his sister Usagi, [[LovesMyAlterEgo whom he has a far more adversarial relationship with]].
77** Chibiusa is Usagi and Mamoru's KidFromTheFuture. As soon as she arrives in the present, she gets an AccidentalKiss with Mamoru. She is attracted to her own father and competes with Usagi for his affections. The surprise is on Usagi and Mamoru's side when they eventually find out who she really is.
78* Averted in ''Literature/{{Slayers}}'': Thankfully, Zelgadis stating that Rezo was both his grandfather and great-grandfather turned out to be a translation error.'
79* Falan and [[spoiler:Ilsaid]]'s dad in ''Manga/VampireGame'' did not inform them that they were related, until his son asked for his sister's hand, that is. He then only told his [[TheUnFavourite Unfavorite]], though.
80* ''Manga/VampireKnight'': When Kaname turns Yuuki into a vampire, restoring her memory, she reveals to the audience that Kaname is her brother. Ah, so the LoveTriangle will be easily solved, won't it? ''Wrong''. Kaname confirms she's his sister and states she was ''born to become his wife''. Then he asks the other why they look surprised -- [[DeliberateValuesDissonance this is very common among pureblood vampires]], and in fact, their own parents (Juri and Haruka) were siblings and HappilyMarried. [[spoiler:Later it turns out that Kaname wasn't her brother, but a distant ancestor who had been asleep for hundreds, if not thousands, of years and her real brother was given to him as a blood sacrifice so that he could be revived. It's still incest so it's [[DoubleSubversion double subverted]].]] The situation is exactly as complicated as it sounds.
81[[/folder]]
82
83[[folder:Comic Books]]
84* ''ComicBook/AgeOfBronze'': One of the chieftains mentions he unknowingly married his mother, but fortunately a snake showed up in the marriage chamber in time to prevent it from happening (and then they learn they're related, so they attribute the serpent's presence to his father Herakles intervening).
85* ''ComicBook/{{Blacksad}}'': [[spoiler:Hans Karup]] unknowingly married one of his own daughters after she came of age. She was actually aware of their family relationship, and [[LysistrataGambit wouldn't let him touch her]]. The marriage was in fact all part of a decades-long revenge plot to hurt him for previously leaving their mother to her death.
86* ''ComicBook/ElfQuest'':
87** It may never have been revealed to the characters, but Cutter once got it on with Kahvi during a pre-battle orgy, and Kahvi takes up with him while Cutter's family is lost in time, though it doesn't really work out. Much later, readers learned that Kahvi is the daughter of former Wolfriders chief Two-Spear. Cutter is a direct descendant of Two-Spear's half-sister, Huntress Skyfire, making Kahvi his cousin four times removed -- which, especially considering the small gene pool of the Wolfriders, isn't spectacularly close. Also, with Recognition preventing conception for any but good genetic combinations, the elves may not ''have'' an incest taboo.
88** Also, if one looks at Scouter/Tyleet's relationship, you'll realize they're second cousins (Brothers Longbranch and One-Eye, Longbranch sires Nightfall, One-Eye sires Scouter, Nightfall has Tyleet, Scouter and Tyleet Recognize). It makes sense, however, that such in-pairings will happen in such a small tribe -- so yes, Recognition probably does take care of the biggest problem with incest. Thankfully, however, we haven't been subjected to any ''closer'' pairings...
89* [[spoiler:Jack]] from ''ComicBook/{{Fables}}'' doesn't find out that he's adopted and that the Page sisters are also his half-sisters until after he's already slept with each of them. He takes the news [[{{Pun}} relatively]] well, his sisters, [[BrainBleach not so much]].
90* A story arc in ''ComicBook/TheFabulousFurryFreakBrothers'' has Fat Freddy looking for his old home in Cleveland, broke, hungry, and bemoaning his perpetual bad luck. Just then, to his delight, a cute girl appears, befriends him, takes him home, feeds him, and joins him in the bathtub. A car pulls in and she warns "Here come my parents!" -- Freddy sees them and exclaims "Holy Toledo, these are ''my'' parents too!"
91* ''ComicBook/JimmysBastards'': Jimmy Regent (a Film/JamesBond parody) turns out to have spawned an entire army of, well, bastard children over the years with every GirlOfTheWeek, many of which have united for revenge against him for not being helping raise them. The villain's plans hinges on getting Jimmy to sleep (unknowingly) with his daughters and reveal this at the opportune moment to break him. [[HeroicBSOD It works]].
92* ''Magazine/{{Mad}}'' occasionally uses this.
93** In a list of cliché movie props, one Arab beggar reunites his necklace with that of the Caliph's daughter, whom he loves, and in doing so, learns that they are brother and sister. [[ShaggyDogStory The love affair ends before it starts]].
94** In the parody of ''Maverick'', the [[WhamLine final line]]:
95--->''There's still one final plot twist -- you can't marry your own sister!''
96* In ''ComicBook/ManyHappyReturns'', Kara Zor-El (the original ComicBook/{{Supergirl}}) and Kon-El (ComicBook/{{Superboy}}) meet and find each other cute (Kara is visibly smitten with him). Neither of them knows at the beginning that Kara is a cousin of Kon's genetic template.
97* ''ComicBook/TheMightyThor'': In an issue of Creator/JasonAaron's run, a young version of Thor is pulled out of the distant past and enslaved on a world full of Gods who have been kidnapped from various eras of history. He meets three beautiful young goddesses, sisters. While two of them are unimpressed by him, one, Ellisiv, is [[EatingTheEyeCandy enjoying the sight of a young Thor in a loincloth]]. They turn out to be his descendants from the far future.
98-->'''Ellisiv:''' Thor? Oh my Heavens... I've been having impure thoughts about my ''grandfather''.
99* ''ComicBook/{{Shazam}}: The Monster Society of Evil'' has a thankfully low-key example: Mary seems to have a PrecociousCrush on the superhero who just [[RescueRomance saved her from being eaten by alligator-men]] and kisses him on the cheek, only to find out a few pages later that he's actually the OlderAlterEgo of her [[LongLostRelative long-lost big brother]]. She thinks it's gross, but he's so happy to have tracked her down that he's just amused by the whole thing.
100* Played with in ''ComicBook/SupermanRedSon''. Although nothing ever comes of it, Superman and Lois Lane are clearly in love. It's revealed at the end of the comic that [[spoiler:Superman is not an alien but a highly evolved human from the far future sent back in time as a baby, and he is a distant descendant of Lois and her husband Lex Luthor. That being said, the family connection is so many generations removed that they're probably no more genetically related than any two random people]].
101* In the Creator/ECComics ''Weird Science'' story "The Last Man" (#12, 1952), a man returns to Earth after a long space journey only to find it removed of any humans. After a long search, he finally finds a woman, but before they can make plans to [[AdamAndEvePlot repopulate humanity]], they shockingly [[ContrivedCoincidence discover that they are brother and sister]].
102* ''ComicBook/XMan'': After he arrives in the 616 reality, Nate Grey is found by a redheaded young woman called Maddie, who's lost most of her memory. She turns out to be Maddie Pryor, clone of Jean Grey, who Nate [[PowerIncontinence accidentally resurrected]] when subconsciously reaching out for the 616 version of Jean. Why would Nate have reached out to Jean? Why, she's his genetic mother -- and thus, so is Maddie. The resemblance didn't matter -- he'd only met his reality's version of Jean once, and had sensed a connection, even if he didn't know what it was. Anyhow, Nate and Maddie get along remarkably well, building a connection and a developing sense of UnresolvedSexualTension, which the narrative (and some fans) gleefully fanned the flames of. Then Nate found out about his connection to Jean and Maddie -- thankfully before they'd got closer than an AlmostKiss or two. He backed off sharply. Maddie, on the other hand, was a textbook {{Tsundere}} (to occasionally [[MurderTheHypotenuse murderous]] extents) whose [[IfICantHaveYou attitude]] was neatly summed up by [[https://static.wikia.nocookie.net/marveldatabase/images/7/75/X-Man_Vol_1_41.jpg/revision/latest?cb=20080519172859 the notoriously suggestive cover]] to issue 41.
103[[/folder]]
104
105[[folder:Fan Works]]
106* In ''VisualNovel/ApolloJusticeAceAttorney'', we see the protagonist, Apollo Justice. His attractive assistant is Trucy Wright, Phoenix Wright's daughter. They got a bunch of ShipTease in-game until it was revealed that Trucy was adopted, and she's Apollo's half-sister through their mother Thalassa. Oddly, it still hasn't stopped the fan pairing from still occurring. This is probably because while the ''players'' learn that Trucy and Apollo are related, [[DramaticIrony they themselves never do]] (although at the end of ''VisualNovel/PhoenixWrightAceAttorneySpiritOfJustice'', Phoenix and Thalassa decide it's time for them to know).
107* In ''Fanfic/TheDarknessSeries'', a Voldemort/Harry fic, Harry learns he's related to Voldemort on both sides of the family tree. [[VillainousIncest They don't think too hard about it.]]
108* ''WebVideo/DragonBallZAbridged'':
109** A half-example happens, that is possibly an {{Homage}} to ''Film/BackToTheFuture1''. Trunks travels back in time but keeps quiet about being a time-traveler so he doesn't change the past. Then his future mother Bulma starts hitting on him:
110--->'''Bulma:''' So hey, like just gonna throw this out there: you're really cute.\
111'''Trunks:''' Well, you know, my mom always said I was a cute kid...\
112'''Bulma:''' Oh a momma's boy huh? [[RightForTheWrongReasons I'll be your mommy.]] (''wink'')\
113(''[[TheUnSmile Trunks forces a smile]] while [[ScreamingAtSquick screaming in his head]]'')
114** Upon finding out the truth a few years later:
115--->'''Bulma:''' Oh my god, I solicited my son for sex.
116** What makes this hilarious though, is that once Trunks returns to the future to report on his progress, Future Bulma is rather nonplussed at the idea that her past self hit on him:
117--->'''Trunks:''' Before you found out I was your son, in the past, you... might have made a pass at me.\
118'''Bulma:''' Well ''duh''.\
119'''Trunks:''' MOM!\
120'''Bulma:''' Hey, it's not ''my'' fault your dad's genetics and mine got along like chocolate and peanut butter.\
121'''Trunks:''' [[FridgeHorror Is... that why you used to call me your "little peanut butter cup]]?!"
122* Played straight in the ''WesternAnimation/AvatarTheLastAirbender'' fanfic ''Fanfic/EmbersVathara'' where it is revealed that the relationship between [[spoiler: Zuko and Mai]] was a secret case of KissingCousins orchestrated by [[spoiler: Azula]] in order to have leverage on them.
123* The ''WesternAnimation/HowToTrainYourDragon'' fic "[[https://www.fanfiction.net/s/14170808/1/Berserkers-Hooligans Berserkers & Hooligans]]" reveals that Heather has secretly been essentially Hiccup and Astrid's on-off mistress for years, to the extent that only the three of them know that Hiccup is the father of Heather's son Oswald. During one visit after the dragons leave, Hiccup and Astrid's daughter Zephyr is dared to kiss Oswald, and the three parents are momentarily concerned before Zephyr makes it clear that she found the kiss disgusting and compared it to kissing her brother without even knowing that Oswald ''is'' her brother, assuring the parents that they have no concerns on that front (although they still make plans to at least tell their children the truth about Oswald's parentage).
124* Technically at least referenced in ''Fanfic/AnExtraordinaryJourney''; when [[spoiler:the SGC, the remaining Cylons and the survivors of the Twelve Colonies find a survivor on the Earth of the Thirteenth Tribe, she is swiftly identified as the source of the DNA used to create the Number Six Cylon, who reveals that the Number Twos are based on her father. As a result, technically any Twos and Sixes who have gotten involved are committing incest, with the Two present when she reveals their connection quickly expressing discomfort at this revelation]].
125* ''Fanfic/FatesCollide'': Mercury Black is attracted to Ushiwakamaru, but is unaware she is his long lost sister. She knows of their relationship, but doesn't have the heart to tell him and is apparently unaware of his attraction. [[spoiler:When he eventually finds out, he is shocked, but then becomes happy he has a family member who cares about him and they have a normal sibling relationship.]]
126* The dōjinshi ''VideoGame/GoldenSun Gag Battle!'' featured a 4koma in which Ivan's first use of Reveal was to spy on Hama through her clothes. ''Gag Battle'' was based on the first game and published prior to the release of the second, which revealed that Hama was Ivan's sister, making this a meta example. Mia and Alex, another popular pairing due to their shared history, were revealed to be cousins in ''Dark Dawn''.
127** While not strictly an example since they and the fans know darn well they're related, the fandom's unofficial name for the Felix×Jenna pairing is "[[LampshadeHanging Oopsie-shipping]]".
128* In ''Fanfic/{{Hard Reset|Eakin}}'', Twilight figures she might as well use a GroundhogDayLoop to have a one-night-stand with Princess Luna. In the sequel, she finds out she had, long ago, another suitor. One that Twilight's also attached to in a way. [[spoiler:Celestia then reminds Twilight that 1,600 years is probably sufficient time. 'You’re probably more closely related to a random unicorn wandering the streets of Canterlot, genetically speaking.']]
129* ''Fanfic/HigherLearning'': While [[spoiler:Shinji was stuck into the Twelfth Angel]] Asuka [[spoiler:turned to Kaoru to have a shoulder to cry on. After he spent a while reassuring her, she felt something familiar on him and kissed him on impulse. Right away she felt guilty, got scared and ran away.]] At the next morning, Kaoru apologized and said he would resign if she wanted, but she said not and apologized in turn. They never brought it up again, not even when [[spoiler:Kaoru confessed that he was her GRANDSON.]]
130* Narrowly avoided in ''Fanfic/HowToBreakAFamily''. Arthur is convinced to see a prostitute but is turned off when it turns out she's only fourteen. He finds out a moment later that she's his sister Kate. The two were separated when their parents divorced fourteen years prior.
131* Due to the growing relationship between [[{{Polyamory}} Asuka, Rei and Shinji]] in ''Fanfic/NeonMetathesisEvangelion'', Rei and Shinji are headed that way.
132* In ''[[http://percyjacksonfanfiction.wikia.com/wiki/Love_Kills Love Kills]]'', a ''Literature/PercyJacksonAndTheOlympians'' fanfiction, [[spoiler:the main character, Jade, falls in love with Luke only to find out that he's her brother]]. You'd think his name would have been a giveaway.
133* ''Fanfic/MomentaryWeakness'': Downplayed. Sena invites Nia back to her bedroll, unaware that Nia is her HonoraryAunt (she doesn't even know what an aunt ''is'', as she's only been recently been introduced to the idea of families). Nia politely declines, noting that she's HappilyMarried... and then, when Sena isn't paying attention, mutters that Sena's mothers would murder her if she took advantage.
134* A brief example of this features in the ''Series/Charmed1998'' fanfic ''Fanfic/OnceAndFutureWitches'', when circumstances prompt the Charmed Ones of 2007 to go back in time six years accompanied by Chris (who has come back from the future when Wyatt was attacked by a curse). Once they have assured the Charmed Ones of 1999 that they’re real, the young Phoebe asks if Chris is “[her] own hunk of Whitelighter”, leaving her older self embarrassed and young Phoebe herself disgusted once older Piper clarifies that Chris is her future son, and hence Phoebe’s nephew.
135* In the ''Frozen'' fanfic ''Fanfic/TheQueenOfHearts'', [[spoiler:Hans]] was a ChildByRape conceived during a war. He was raised in [[spoiler:the Southern Isles]], not [[spoiler:Arendelle]] alongside his half-sisters [[spoiler:Elsa and Anna (both of which he tried to marry)]]. His parents tried to avoid this by never having the half-siblings meet, but [[spoiler:Hans]] found his way to [[spoiler:Arendelle]] anyway.
136* Played for tragedy in the ''Franchise/StarWars'' fanfic ''[[https://www.fanfiction.net/s/2080032/1/The-Shadows-Suit-Me The Shadows Suit Me]]'' between Luke and Leia.
137* ''Fanfic/SomosFamilia'': Downplayed. [[spoiler:Ignacio tries to woo Coco, whose father turns out to be his half-brother. However, Coco only returns his interest as a knee-jerk reaction after getting into a fight with Julio. She dislikes Ignacio and quickly dumps him before their relationship gets physical.]] Additionally, [[spoiler:the only character to learn about their relationship so far is Hector, who is too busy processing his father's identity to reflect on Ignacio pursuing Coco.]]
138* The ''Frozen'' fanfic ''Fanfic/StolenIce'' has this occurring to Elsa and Anna. They were separated at a young age but come across each other as adults and fall in love. They don't learn they're sisters until late into the story.
139* ''WebVideo/SwordArtOnlineAbridged'' gets into this despite changing Kazuto and Suguha's relationship from an unrequited BigBrotherAttraction[=/=]KissingCousins deal to something [[BigSisterBully much more antagonistic.]] After bumping into each other one evening in ''Alfheim Online'', Leafa is able to figure out that the Spriggan she's been adventuring with is her brother Kazuto after he properly introduces himself as Kirito. She logs out to have a ClusterFBomb-ladden rant because she was just caught [[TheRoleplayer roleplaying]] by someone she constantly mocks, ''then'' remembers an even more embarrassing detail:
140-->'''Suguha:''' Oh Jesus fuck, I said my brother had a ''sweet patootie!'' ''[shrieks and begins sobbing into her pillow]'' Noooo, ''nooooo'', NOOOOOO!!
141* In the ''WebAnimation/{{RWBY}}'' fic ''[[https://www.fanfiction.net/s/13173527/1/Unexpected-Sisters Unexpected Sisters]]'', Yang and Ruby are co-workers who find out that they're half-sisters. In hindsight, it makes the time Ruby asked Yang out (and she declined) even more awkward.
142* ''Fanfic/WhiteSheepRWBY'':
143** Subverted. Due to some coincidences and assumptions, Qrow believes that Jaune is his sister Raven's son, and therefore his niece Yang's half-brother. Since they're kind of dating at this point, Qrow is horrified, and tries to sabotage their burgeoning relationship. [[SpringtimeForHitler This actually leads to their relationship getting stronger]]. Thankfully, Qrow was wrong, and Jaune is not related to Yang at all.
144** And then there's the moment where Qrow discovers the girl he is in the middle of having sex with is Jaune's sister--while he still believes Jaune is Raven's son. There is a ''lot'' of screaming.
145* ''Good News and Bad News'' (an M-rated MLP fic): Twilight's been dating Flash Sentry, and when she discovers she's pregnant, they go to tell Twilight's father... but before they can say anything about it to him, he happily greets Flash as "my boy" and, at Twilight's confused reaction, admits that Flash is his son from his first marriage. The couple are stunned when they realize what this means for them.
146* One-sided example in ''Fanfic/YinYang''. Adam flirts with Adora when they first meet, but she isn't interested in him at all. After they learn that they are siblings, Adam is ''really'' glad Adora rejected him.
147-->'''Adam:''' I... I'm not sure how I feel about this. Other than that I've never been so happy to be rejected by a girl in all my life.\
148'''Adora:''' Yeah... lucky us.
149* In ''Fanfic/GoingAnotherWay'', after being Rei's girlfriend for several months, Shinji learns that, because Yui Ikari's DNA was used to create Rei, they're technically siblings. However, due to the countless other women who's DNA was also used to create Rei, the amount of Yui's DNA that actually makes up Rei is less than 1%.
150* Played with in ''Fanfic/SiblingRevelry'', in that the Empire at large is under the impression Luke and Leia are in a romantic relationship, so when Vader learns early they're siblings he tries repeatedly to have this sprung on them before she gets pregnant. Too bad that by the time they find out they're trolling a "Fred Antilles" (Vader's spy on the Home One) by pretending they're romantically attached because he's opposed and finding out only makes them pretend they're ''happy''.
151* In ''Fanfic/LacrimeDoroDelVentoAureo'', [[Manga/JoJosBizarreAdventureGoldenWind Giorno]] has a brief crush on the visiting [[spoiler:[[Manga/JoJosBizarreAdventureDiamondIsUnbreakable Josuke]]]]. [[DramaticIrony Unbeknownst to Giorno]], the two are actually relatives and part of the Joestar family[[note]]For clarification, Giorno is the illegitimate son of [[Manga/JoJosBizarreAdventurePhantomBlood Jonathan Joestar]] after Dio stole his body, while [[spoiler:Josuke is Jonathan's great-grandson]][[/note]].
152* In this ''VideoGame/FateGrandOrder'' [[https://imgur.io/gallery/6kuTgtA fancomic]], it's heavily implied that this is the reason Lancelot feels ill after finding out that his adoptive mother Nimue was a split personality of Morgan. The reason is that Lancelot harbored feelings for his king Artoria (enough that [[ContinuityNod he conspired with Gawain to convince her Lancer self into wearing a bunny suit]]), and is horrified to learn that she's actually his adoptive aunt.
153* Invoked in ''Fanfic/StoneStreak'', where to get Chloe to stop making him her boyfriend, Adrien points out that once Luka and Chloe's older sister Zoe get married, that would make Chloe and Adrien aunt and nephew[[note]]In the story, Adrien was adopted by Juleka and Marinette, which also make Luka his uncle and Zoe his soon-to-be aunt[[/note]].
154* ''[[https://archiveofourown.org/works/49383754 The Final Confession]]'': During Emilie's {{Video Will|s}}, she reveals that as a [[Anime/PuellaMagiMadokaMagica Puella Magi]] she was unable to have children as she was [[spoiler:a soul gem operating a corpse]]. Instead, her son Adrien was originally one of Audrey Bourgeois's twins[[note]]Though Emilie doesn't consider Audrey worthy as a mother given she was quick to report as only giving birth to a daughter rather twins[[/note]]. After watching, Chloe, horrified that the boy she had a crush on was her twin brother, vomits in a nearby trash can.
155[[/folder]]
156
157[[folder:Films -- Animation]]
158* InUniverse in ''WesternAnimation/{{Encanto}}:'' [[spoiler:Bruno]] creates elaborate ''telenova'' storylines for his pets to act out, one of which involves an amnesiac woman unknowingly in love with her nephew.
159* Kind of inverted in ''WesternAnimation/MeetTheRobinsons''. Lewis goes to the future, spends time with the Robinson family, and begins to see Franny as a bit of a mother figure (even actually calling her mom and almost being adopted by her at one point) before finding out that [[spoiler: she is actually his future wife]]. One wonders how he wasn't the least bit {{squick}}ed out when [[spoiler: he meets her for the "first time" in the past]].
160[[/folder]]
161
162[[folder:Films -- Live-Action]]
163* ''Film/SeventeenAgain2009'': Maggie is attracted to and tries to seduce "Mark"... who is her father, Mike, aged down. Mike understandably rejects her advances. She never learns about the fact, though.
164* ''Film/ABCsOfDeath2'': At the end of "Z is for Z[[spoiler:ygote]]", the husband is about to take his 'wife' to bed to make another baby after she tells him that she has lost the child she was carrying. [[spoiler:If you believe that the child has taken over her mother's body and is wearing her skin (and this is not just a delusion of the mother), then this would be a case of incest.]]
165* In ''Film/AngelHeart'', Harold Angel is investigating the disappearance of Johnny Favorite. In the process, he has sex with Johnny's biracial daughter Epiphany Proudfoot. It turns out that [[TomatoInTheMirror he himself is Johnny later on]]. To make matters worse, [[spoiler:he later killed her while under Satan's influence.]]
166* Inverted in ''[[Film/CaveDwellers Ator the Fighting Eagle]]'': Ator and his sister Sunya are "in love" and want to marry, only later to find out that Ator was adopted, meaning they aren't siblings at all and can now safely marry.
167* Factors into TheReveal in ''Film/AugustOsageCounty'', but not the way the characters expect. Growing up, protagonist Barbara and her sisters had just one cousin on their mother's side, known in the family as Little Charles. Middle sister Ivy eventually admits to her sisters that she and Little Charles have fallen in love, as a result of him helping her through a bout with cervical cancer that no one else in the family knew she had. Barbara finds this awkward, but not horrifying, especially since Ivy's unable to have children as a result of her cancer surgery. [[spoiler:Then their aunt (their mother's sister) reveals to Barbara that Little Charles is actually their ''half-brother'', the result of her having an affair several years ago with Barbara's father.]]
168* In the film ''Film/AnAwfullyBigAdventure'', P. L. O'Hara, an aging actor, seduces a teenage girl, only to find out later that she's his daughter. [[spoiler:The distraction caused by this discovery leads to his death.]]
169* Parodied in ''Film/BackToTheFuture1'' where Marty knows that young Lorraine will be his mother, but she doesn't, so she pursues him romantically to his great dismay. The attraction conveniently disappears after she kisses him, saying that it was like kissing her brother. Chalk it up to [[GutFeeling women's intuition]], [[RubberBandHistory the timeline trying to correct itself]], or just [[MaybeMagicMaybeMundane finally cottoning on to Marty's obvious discomfort]].
170* The major couple in ''Film/TheBeastmaster'' turn out to be cousins, though not one person ever remarks on this. Considering that she's described as his half-brother's cousin, maybe they're [[NotBloodSiblings not blood cousins]] after all. She could always be the niece of the king's second wife.
171* The Japanese film ''Film/BubbleHeNoGo'' has a father sending his daughter (who doesn't know he's her father) back in time some 20 years to find her mother, only to find her younger father instead, who tries to shag her, but she refuses, only to almost give in but then he shortly before realizes that... and so on.
172* ''Film/Code46'' deals with a future where, due to extensive cloning, there is a likelihood of a close genetic relationship between perfect strangers. Maria becomes pregnant by William, only to discover that, biologically, she's his mother; [[spoiler: due to the laws, the baby is aborted and Maria's memories are modified to forget she ever met William, but unfortunately, nobody told William. He finds her again, only this time their intimacy triggers an implanted suggestion, causing Maria to turn herself and William in, this time resulting in a memory wipe for him and for her exile with her memories intact]].
173* In ''Film/CurseOfTheGoldenFlower'', [[spoiler:Chan and Wan]] eventually find out they're half-siblings, and take it [[FreakOut about as well as you'd expect]].
174* PlayedForLaughs in ''Film/DirtyWork'': the two best-friend protagonists find out they are actually half-brothers. One of them becomes upset with the revelation, and the other cheers him up by reminiscing about their childhood, pointing out they practically grew up like brothers anyway. At first, it goes fine, until...
175-->'''Mitch:''' Hey, hey! Hey, you remember in 5th grade when I was under the monkey bars and I sneaked a peek at your sister's underwear? Remember that? Hey, no no! I was sneaking a peek at my ''own'' sister's underwear!\
176'''Sam:''' That's right! Yeah, and then remember in the 12th grade, you had sex with her?\
177'''Mitch:''' ''[short awkward silence as the FridgeHorror hits them both]'' Okay, enough reminiscing.
178* ''Film/FuneralParadeOfRoses'': Gondo gets a very unpleasant surprise when he gets a look at Eddie's photo and recognizes the man with the burnt-out face, Eddie's father...it's him. (It's a GenderFlip update of ''Theatre/OedipusTheKing''.)
179* Becomes a main plot arc in ''Film/{{Incendies}}'' when [[spoiler: the twins discover when their mother sent them to find a lost brother and their lost father, that the person is in fact the same]]!!!
180* In Japanese film ''Film/{{Inugami}}'', [[spoiler:Miki and Akira]] discover that they are mother and son. They also discover that [[spoiler:Akira]] is a product of [[BrotherSisterIncest another, similarly themed trope]].
181* In the film ''[[Film/ManonDesSources Jean de Florette]]'', Le Papet (Creator/YvesMontand) and his nephew Ugolin (Creator/DanielAuteuil) drive a hunchback, Jean (Creator/GerardDepardieu), to his death in order to get his land. In the sequel ''Manon of the Spring'', [[spoiler:Ugolin sees the hunchback's daughter Manon (Creator/EmmanuelleBeart) bathing in a pond and falls desperately in love with her. He commits suicide when she rejects him. At the end, his uncle Papet learns that Manon's father was his long-lost son. That means Ugolin was in love with his own cousin]].
182* Parodied in ''Film/JoeDirt'' -- in Joe's quest for his lost family, he finds and goes out with an attractive girl who he realizes afterwards was his sister, goes back to tell her and explain why he can't date her (and probably ask her for information), but somehow gets seduced into sleeping with her, ''then'' tells her his suspicion. She then explains why she couldn't possibly be his sister, and that they can make love again. Joe puts on a mischievous face and the camera cuts back to the outside of the house... [[TheLoinsSleepTonight as nothing happens]].
183-->'''Jill:''' Would it help if you went back to thinking I'm your sister?\
184'''Joe:''' What?! Like I'm some sort of white-trash perv?!\
185''[cut to the outside of the house, the foundations shaking and a nailed-up hubcap clattering off to orgasmic cries]''\
186'''Jill:''' I'm your sister! ''I'M YOUR SISTER!''\
187'''Joe:''' ''AAAAAAAAAHHHH YER MY SISTER!''
188** Joe then assures the radio people he's telling the story to "No, that last part didn't really happen, [[ItAmusedMe I just thought it'd be funny]]."
189* In ''Film/TheJudge'', Hank seduces a girl in a bar. Then finds out she is the daughter of an old flame. And the math makes it possible to be Hank's as well! [[spoiler:It turns out she's his niece, as the disgruntled ex slept with Hank's brother.]]
190* ''Film/{{Kaboom}}'': In the climax of the film, it is revealed that [[spoiler:Smith and London are half-siblings, both having the same father]]. This is a nasty surprise for them, since they've been boning regularly through the movie.
191* In the original cut of ''Film/KateAndLeopold'', Kate's ex-boyfriend is Leopold's great-great-grandson. Due to StableTimeLoop, this means Kate's ex, who she spent years with, is also ''her'' great-great-grandson, something that hadn't occurred to the director. This is excised from the theatrical version, but remains in the director's cut.
192* In ''Film/LoneStar1996'' [[spoiler:two characters that had dated in high school over their parents' STRONG objections reconnect as adults. At the time, they had assumed their parents objected out of racism as he is white and she is Hispanic (with the story taking place in the south). They later find a photograph of his dad and her mom and realize why their parents were so opposed to them dating, namely, that they're half-siblings with the sister being born out of an affair. But they're very much in love and she says that, due to complications in her last pregnancy, she can no longer have children. It's implied that they will stay together]].
193* ''Film/MyChauffeur'' flirted with this. As one of several [[TheUnreveal seeming reveals]] about who the female lead's "real father" was. Apparently, Mom got around.
194* Invoked in ''Film/NuttyProfessorIITheKlumps'' when Grandma Klump tries to seduce Buddy Love when mistaking him for the stripper for a bachelorette party, unaware that Buddy is essentially a genetically-altered clone of her grandson.
195* ''Film/{{Oldboy|2003}}'', in which the main character is the victim of an elaborate revenge/imprisonment plot, [[spoiler:the final result of which leads him to discover that the woman he has fallen madly in love with is, in fact, his daughter. He, uh, doesn't take it so well]].
196* In the drama film ''Film/PowderBlue'', a stripper (Jessica Biel) whose young son is in a coma, performs a lapdance for a middle aged male customer (Ray Liotta) there to see her. Unbeknownst to her, the man she's giving a lapdance to is actually her long-lost ''father'' and the man, appropriately repulsed, moves her hands and body away from him as he just wants "a hug, not a tug".
197* In ''Film/RedRidingHood,'' [[spoiler:Lucie was in love with Henry, but doesn't realize that they share a biological father]]. Fortunately, nothing actually happens between them. ''Un''fortunately, it factors into a couple deaths.
198%% * This is the whole plot behind ''Film/SayItIsntSo''. Faux-Farrely hijinks ensue.
199* In the Michael J. Fox film, ''Film/TheSecretOfMySuccess,'' Brantley is asked to escort the wife of his boss to her country home. She takes an immediate liking to him and convinces him to [[TwoPersonPoolParty stay for a swim, which leads to her seducing him]]. Not long after, Brantley realizes that she is his Aunt Vera (by marriage, as his boss is his blood-related uncle, Mr. Prescott). Brantley is disgusted, but Vera isn't - she later pursues him sexually.
200* In ''Film/{{Soapdish}}'', Jeffery starts dating his ex-girlfriend Celeste's young protege Lori. Celeste strongly objects to this, but they shrug it off as jealousy. Celeste is finally forced to admit that Lori is their daughter. Celeste and Jeffery separated a long time ago and she did not inform him that she was pregnant. While raising Lori, she told her she was adopted. Jeffery and Lori are horrified but glad they were stopped before they could kiss.
201* In the American college comedy ''Film/SororityBoys'' a character, Jimmy becomes infatuated with his former frat brother and actual biological older brother Adam while the latter is DisguisedInDrag for plot reasons. Adam, naturally, tries desperately to fend off his unwitting brother's advances without blowing his cover. This is played for laughs over the course of the movie until [[spoiler: a scene where it is heavily implied Jimmy raped Adam while "she" was passed out in his room.]] Needless to say, after TheReveal, things become very awkward between them.
202* {{Enforced}} in ''Franchise/StarWars'' due to a series of script rewrites and {{retcon}}s. ''Film/ANewHope'' suggests Luke Skywalker has a crush on Princess Leia Organa,[[note]]Creator/AlanDeanFoster's novelization and the first comic book adaptation, ''ComicBook/StarWarsMarvel1977'', and ''Literature/SplinterOfTheMindsEye'' make it explicit and mutual[[/note]] and it and ''Film/TheEmpireStrikesBack'' have a minor LoveTriangle between them and Han Solo: at one point, Leia kisses Luke on the mouth, but [[BelligerentSexualTension the movie makes it reasonably clear she did it just to spite Han]]. After ''Empire'', however, Creator/GeorgeLucas decided to [[WhatCouldHaveBeen cancel the then-planned sequel trilogy and condense its major storylines into a single film]], which became ''Film/ReturnOfTheJedi'': the "other last hope" that Yoda and Obi-Wan refer to in ''Empire'' was originally just meant to remove Luke's PlotArmor as the main character, but became Luke's sister from whom he had been SeparatedAtBirth,[[note]]an idea originating in early versions of ''The Star Wars'', which became ''Film/ANewHope''[[/note]] and Leia was the only established character his sister could somewhat-plausibly be. In subsequent ExpandedUniverse media, the siblings invariably say [[LetUsNeverSpeakOfThisAgain they try not to think about it]] on the rare occasions it's brought up.
203* ''Film/ThatNightInVarennes'': Restif the pornographer, in one of his dirty books, tells a story of having sex with a High-Class Call Girl and only finding out afterwards that she was his daughter. Of course, since the movie shows he's actively engaged in an incestuous relationship with a different daughter, he probably wasn't bothered.
204* ''Film/ThreeSeatsForThe26th'', a French movie where Yves Montand plays himself and buxom sex bomb Mathilda May plays his illegitimate daughter Marion (a character created for the movie, not based on any real person). They meet and immediately feel attracted to each other and eventually sleep together. At some point, Marion's mother tells her that Montand is her biological father, Marion reacts... with a cute "oopsie!" face and isn't bothered at all by TheReveal. Montand, however, '''is''' pretty horrified but after seeing Marion's nonchalant attitude towards the whole mess, he relaxes and realizes that perhaps ParentalIncest isn't such a horrid taboo, all things considered. They all become a happy family.
205* In ''Film/TromeoAndJuliet'', the eponymous pair find out at the end they're brother and sister, but decide to get married anyway. In true Troma fashion, they have hideously deformed kids.
206* In ''Film/WarInc'', Yonica keeps hitting on Hauser, which creeps him out because she's a teen and he's an adult. [[spoiler: At the end, they find out they're father and daughter.]]
207* In the extended cut of ''Film/WildThings'', Suzie is revealed to be Kelly Van Ryan's aunt (whose grandfather was a notorious philanderer). As part of Suzie's scheme to con her older half-sister Sandra Van Ryan (Kelly's mom) out of millions of dollars, she knowingly had sex with her own niece several times. Although no one except Suzie was ever aware of this and Kelly never learns the truth.
208* The 1920 silent film ''Film/WithinOurGates'' has a flashback to the protagonist almost being raped by a white man. He then notices that she has the same distinctive birthmark on her chest that his daughter with his ex-wife did. Sylvia herself has quite a complex about the fact she's half-white.
209
210* In ''Film/{{Zathura}}'', Lisa immediately starts harboring a crush on the astronaut once she awakens after having been [[HumanPopsicle being frozen]] for most of the movie. He tries to brush off her advances, presumably because she's underage. Later in the film [[spoiler: it's revealed that the Astronaut is actually her little brother Walter from an alternate future. She's... less than pleased]]. (Since it's a space-themed sci-fi film, this could debatably be considered a loose ''Star Wars'' reference.)
211[[/folder]]
212
213[[folder:Jokes]]
214* Subverted in a joke where a young man tells his father he's going to ask out the girl next door. His father looks grave and says "You can't. I've never told anyone this, but you need to know ... many years ago I had an affair with her mother, and, well..." Horrified, the young man runs out of the room where his mother asks what the problem is. He explains "I'm in love with the girl next door, but Dad says he's her father!" And his mother replies, "Don't worry about that. He might be ''her'' father, but he's not yours!"
215[[/folder]]
216
217[[folder:Literature]]
218* One of the three protagonists in the web serial ''Literature/{{Addergoole}}'' [[spoiler: Shahin]] has an intense romantic affair with another student [[spoiler: Emrys]]. Later, it turns out that they're half-siblings, sharing a father. [[spoiler: This doesn't seem to deter them in the least, as they wind up committing and getting married.]]
219** As a bonus, the couple above is involved in a sort of love triangle with a third person who, unbeknownst to all three at the time, is actually their father.
220* Pops up in Creator/VCAndrews's work (original and ghostwritten).
221** In ''Literature/GardenOfShadows'', [[spoiler: Corrine and Chris, who in prior books were already half-uncle and niece, turn out to be half-brother and half-sister as well (though they seem to be unaware of that part)]].
222** In the second book of the ''Literature/CasteelSeries'', ''Literature/{{Dark Angel|1986}}'', Heaven meets Troy, her late mother Leigh's step-uncle. They fall in love, have sex, and get engaged when [[spoiler: Tony, Troy's brother and Leigh's stepfather, reveals to Heaven that she was the product of Tony's rape of Leigh, making her and Troy niece and uncle by blood]].
223** The ''Literature/CutlerSeries'' has Dawn going out with Philip Cutler, only to learn that she's his long-missing sister. Dawn wants to leave the relationship behind, but Philip doesn't [[SanitySlippage take it]] [[RapeAsDrama well]].
224** At the start of the ''Literature/LandrySeries'', Ruby is dating Paul but quickly ends their relationship when her grandmother reveals to her that Paul is her half-brother. Paul takes it better than the above-mentioned Philip, but he never truly gets over Ruby.
225* Severian of ''Literature/TheBookOfTheNewSun'' never knew who his family was, so this was always possible given the number of women he took to bed. At the end of ''Citadel'' he discovers that [[spoiler: Dorcas is actually his ''grandmother'', who had been drowned decades ago and then returned to life by the Claw]]. He notes that he still loves her, but she loves the past more than him.
226* ''Literature/BoonesLick'': Downplayed. Shay thinks the local prostitute is pretty, but never tries to sleep with her either before or after learning she's his mother's half-sister.
227* In ''Literature/ABrothersPrice'', Jerin and Ren hit it off to the point where he's left a TechnicalVirgin. Then they find out that because his grandmothers [[AbductionIsLove kidnapped a prince]], they share great-great-grandmothers, making them first cousins twice removed, second cousins once removed, or third cousins. Jerin is initially disturbed by this revelation, but Ren says [[KissingCousins it's fine]] and later others agree. Many of the nobility are somewhat more inbred than commoners and actually, this reveal makes him a SuddenlySuitableSuitor.
228* In the first trilogy of ''The Chronicles of Thomas Covenant'' Thomas [[spoiler: is the object of open sexual advances by High Lord Elena, who he eventually realises is biologically his daughter, though (thanks to the time discrepancy between the Land and 'our' world) she actually appears to be older than him. Unsettlingly, she knew all along]]. Though this discovery explains why he finds her emotionally compelling, he continues to wrestle with having some degree of physical attraction to her - made all the more complicated by the fact that he believes his entire experience is a delusion.
229* In Linda Castillo's ''The Dead Will Tell'' William "Hoch" Yoder's wife Hannah is actually Ruth, who was born after his mother Wanetta was abducted, raped, and left for dead following a botched home invasion that resulted in the deaths of her husband and all of her children save William. Ruth maintains her father is Wanetta's murdered husband, but it's more likely [[ChildbyRape it was one of the rapists]]. Either way, after Wanetta died, Ruth created a false identity and married William, knowing full well what they were to each other, for the purposes of {{Gaslighting}} him since he had unintentionally caused the deaths of his siblings by leaving them with a lantern that overturned and sparked a fire and Wanetta held him responsible, which is also why she never let him know she was still alive even after regaining her memories. It's vaguely implied that Ruth causes William to [[DrivenToSuicide take his own life]] by revealing their true relationship at a particularly vulnerable moment for him once he learns his mother actually survived for many more years but wanted nothing to do with him.
230* In the Creator/JinYong novel ''Demi-Gods and Semi-Devils'', all the women Prince Duan Yu has relationships with turned out to be one of his father's natural daughters. Subverted in that Duan Yu was later revealed to be the product of a one-night-stand between his mother and a rival to his father's throne.
231* The Kwisatz Haderach breeding program of the Bene Gesserit in the ''Franchise/{{Dune}}'' series does rather a lot of this if the crosses mentioned in the books are a representative sample. The people involved are generally unaware, at least at the time.
232** According to their plan, Jessica was supposed to have a daughter with Duke Leto Atreides. The daughter was then supposed to be married off to a Harkonnen heir in order to end their millennia-long rivalry. However, Jessica is actually Baron Vladimir Harkonnen's daughter (although she didn't know until Paul told her). This means that the plan was for Jessica's daughter to marry her cousin.
233* Subverted in ''Literature/TheElvenbane'' by Creator/AndreNorton and Mercedes Lackey when Valyn is determined to push away Shana even though he admits that she is lovely and knows that she has a massive crush on him. He does this because he suspects that she is his half-sister. He actually goes so far as to set her up with his sidekick in a "handfasting" ritual. However, he picks up the IdiotBall when he refuses to tell her why he is rejecting her even though she is hurt and angry about it. His excuse? She was RaisedByWolves (or dragons, in her case) and he's not sure if such things matter to her, in spite of the fact that she has already shown herself to be intelligent and fairly well-versed in human and elven culture.
234* ''Literature/CthulhuArmageddon'' volume ''Literature/TheTreeOfAzathoth'' has Booth discovers that [[spoiler: Martha Booth was his biological sister, of sorts, due to the fact that both of them are the children of Alan Ward. This was notably foreshadowed by the fact that Martha and Alan as well as Gabriel (Martha and Booth's son) share the trait of albinism.]]
235* In Frances Burney's 1778 novel ''Literature/{{Evelina}}'', the eponymous heroine saves one Mr. [=MacCartney=] from suicide, since he believes he fell in love with his sister. [=MacCartney=] grows to idolize his savior Evelina in a quasi-romantic fashion. However, at the end of the novel, Evelina is revealed to be his real sister, while his original beloved was an unwitting (and unrelated) impostor.
236* A rare ray of sunshine in ''Literature/TheFirstLaw'' is the romance between Savine dan Glokta and Crown Prince Orso dan Luthar. She's an ambitious social climber, he's a feckless royal layabout. After Savine has a close call in the uprising that forms the centerpiece of ''Literature/ALittleHatred'', Orso proposes marriage, and Savine agrees. She comes home and glowingly tells her mother that she's going to be queen...and her mother is nearly sick. It turns out the man she knew as her father isn't her biological father; her mother was knocked up by the king, and they were married in order to keep her safe. Meaning that Savine and Orso have the same father. She immediately breaks it off with Orso and doesn't tell him why until after a bit of civil war in the next book.
237* At the end of the Marquis de Sade's story "Florville and Courval" (from his collection ''The Crimes of Love'') the heroine discovers that she has unknowingly [[spoiler: had a child by her brother, killed that child in self-defense when he was trying to take her sexually, and married her father.]]
238* In Creator/RobertAHeinlein's ''Literature/{{Friday}}'', the eponymous Friday has a bit of a crush on her father-figure employer, who is later revealed to actually be her father... or at least a male who contributed some of her DNA, Friday's genealogy being somewhat [[DesignerBabies non-traditional]].
239* In ''The Good Daughters'' by Joyce Maynard, Ruth and Dana are born to different families in the same hospital on the same day, and growing up are referred to as "birthday sisters" by their families. As an adult, Ruth dates Dana's brother, Ray, until her parents step in and say something to Ray and he breaks off the relationship. Ruth doesn't learn until much later that she and Dana were switched at birth, making Ray her biological brother, and he had broken up with her because her parents told him this.
240* ''Literature/GrandmasterOfDemonicCultivationMoDaoZuShi'': Jin Guangyao and Qin Su get engaged. Shortly before the wedding Qin Su's mother tells Jin Guangyao that his father raped her, and Qin Su is really his half-sister. He's horrified, especially because they already slept together and Qin Su is pregnant. He goes ahead with the wedding but refuses to touch Qin Su again ([[OffingTheOffspring and may have killed their son to keep the incest a secret]]). Years later she learns the truth. It ends... [[DrivenToSuicide badly]].
241* The incest is averted in ''Literature/{{Havemercy}}'', but just barely. WordOfGod has it that the authors had the brothers in question unrelated in an earlier draft, and deliberately included plenty of sexual tension and the possibility of a relationship between them. Later, they decided to take the relationship in a different direction and proceeded to erase all hints of UST between them. They were fairly unsuccessful, though, as most of the readers picked up on it anyway. Since the fact that they're brothers is hidden until near the end of the book, almost all of the readers were already shipping them by default by the time they found out. And once the ship has sailed, well, there's no calling it back to shore.
242* In ''Hearts of Three'' by Creator/JackLondon it comes as a salvation for the heroine stuck between two guys for both of whom she cares (and who, moreover, are best friends). She loves one of them more passionately but plans to marry another because [[IGaveMyWord they were engaged before she met the other one]]. Practically at the last moment, her fiancé turns out to be her brother.
243* In ''[[Literature/TheMerlinTrilogy The Hollow Hills]]'', the second book in Mary Stewart's retelling of the story of Myth/KingArthur, Morgause, Arthur's half-sister, bewitches him into sleeping with her, and he only finds out afterward of their relation to one another.
244* Max Frisch’s ''Homo Faber''. The novel is mostly just the narrator whining that he really, ''really'' couldn’t have known that the young woman he slept with was his daughter.
245* ''Literature/IAmMordred'': Arthur didn't know Morgause was his half-sister when he had sex with her.
246* In ''Infandous'' by Elana K. Arnold, the teenage protagonist has a brief liaison with a much older man. Some months later she's rummaging her mother's closet and finds an old picture of her then-teenage mother with the guy--turns out he's her father.
247* Henry Fielding seems to like to subvert this trope for particular effect: In ''Joseph Andrews'', the hero thinks for a while that his childhood sweetheart is his sister; while in ''Literature/TheHistoryOfTomJonesAFoundling'', a random one night stand is later seemingly revealed to be the protagonist's mother... Oh NO! Our hero has done something legitimately bad! [[spoiler: Fortunately, this is later resolved to be a lie.]]
248* In ''Literature/KafkaOnTheShore'' by Haruki Murakami, the protagonist begins to have a sexual relationship with an older woman who he suspects might be his mother. She denies it, but it is heavily implied both that she actually is his mom and that she already knows this to be true.
249* The plot of "''Lace''" by Shirley Conran revolves around a movie star named Lily gathering four older women (who have been best friends since boarding school), demanding to know which one of them is her mother. As it turns out, one of the women got pregnant as a teenager and had to place her child in foster care, but for various reasons, her daughter ended up lost and she had no way of finding her. As the story is told the reader doesn't know yet who the mother is and since Lily at one point met and deflowered the son of one of her potential mothers you're left to worry that she might have had sex with her half-brother. In the end, it turns out [[spoiler: that her mother, Judy, never had any other children so Lily hasn't slept with a sibling. Instead, only Judy realizes the true squick factor. When asked who Lily's father is she lies and claims it was a male friend of the girls, but in truth, she was raped by an Arabic prince and became pregnant. That same Arabic prince later took Lily for a mistress and they spent a couple of years having the best sex of their lives with one another. He never knew she was his daughter and because the affair was public knowledge Judy decided to keep the truth from Lily to avoid traumatizing her]].
250* In the final Literature/{{Lensman}} novel, ''Children of the Lens,'' it's all but stated that the Kinnison kids (one boy, four girls) will be the progenitors of the Arisians' replacements.
251* In the crime novel ''Literature/LieToMe'' by David Martin a man kills himself rather messily after finding out that his young wife is really his long-lost daughter. He is particularly distressed by the revelation that she always knew he was her father, but married him anyway.
252* In ''Literature/{{Lirael}}'' by Creator/GarthNix, Prince Sameth shows some interest in Lirael, without knowing [[spoiler: she's his aunt]]. At the time she didn't know either, but she's not interested and puts him off by telling him that she's actually thirty-five but has a marvelous skincare regimen. Later, Nick just assumes they're engaged when he sees them together, and when [[spoiler: he gets set straight and says she looks too young to be an aunt]], Lirael hastily mutters that she's much older than she looks.
253* In ''Literature/LostSouls1992'', [[spoiler:Nothing]] and [[spoiler:Zillah]] begin a sexual relationship and are then informed they're actually father and son; [[spoiler:Zillah]] didn't know he had a son due to abandoning [[spoiler:Nothing]]'s mother shortly before she found out she was pregnant, and she subsequently died. Unusually, they continue their sexual relationship even after learning this, which they justify as them being vampires and therefore not subject to the laws and social norms of humans.
254* In "The Maias", by Eça de Queiroz, Pedro goes a long way until finding out Maria, the married woman he's been obsessing over, is his long-lost sister (not even half-sister or anything). Not that it matters to him.
255* In ''Literature/TheMistsOfAvalon'', a [[FeministFantasy feminist retelling of Arthurian legend]], [[TheChessmaster Viviane]] sets Morgaine up to sleep with her half-brother Arthur as part of a religious ritual. Neither of them recognized the other until after it was too late, and both were suitably freaked out. Viviane can't see what they're upset about.
256* In the novel ''Literature/MollFlanders'' by Daniel Defoe, Moll unknowingly marries her half-brother (her mother having abandoned her as an infant) and has two children with him. Upon discovering the truth, she dissolves the marriage and flees Virginia for England, leaving her two children behind.
257* ''Literature/TheMonk'': As if raping [[TheIngenue Antonia]] wasn't enough, Ambrosio later learns she is his much younger sister.
258* Ultimately {{subverted}} in ''Literature/TheMortalInstruments''. After a first book full of romantic tension, Clary and Jace discover that they're siblings. They spend all of book 2 and most of book 3 angsting about this, until it's revealed that they're not actually related.[[note]]Though granted, Clary's biological dad did raise Jace, so they're NotBloodSiblings who didn't grow up together.[[/note]] Played straight with [[spoiler:Sebastian/Jonathan, Clary's ''actual'' brother, [[VillainousIncest who kisses her despite knowing full well that she's his sister]]]].
259* In ''Literature/OneHundredYearsOfSolitude'', the biggest fear of the matriarch Ursula is that some of her descendants will be born with a pig's tail, in the fear that it could be the end of both her family and the town. This finally happens a long time after her death, when the last members of the family, Amaranta Ursula and Aureliano Buendía, [[spoiler: aunt and nephew respectively,]] mate and give birth to a pig-tailed baby [[spoiler: who is eaten by ants, after his mother dies in childbirth and his father forgot to take care of him because of his deep grief]]. Both lovers were unaware of their real relation, and Aureliano Buendía only discovers it in the last page of the novel, [[spoiler:just seconds before the destruction of the town]].
260* ''Literature/OrlandoFurioso'': The warrior woman Marfisa falls in love with Ruggerio and competes with his fiancee Bradamante for his affections. Eventually, they find out that Marfisa is Ruggerio's twin sister who had been separated from him while they were infants. Marfisa apparently took it well and supported Ruggerio and Bradamante's relationship.
261* Lydiann Ebersol and Jake Mast fall in love and agree to marry in ''The Prodigal'', the 4th book of the [[Literature/AbramsDaughters Abram's Daughters]] series. Unbeknownst to them, Jake is Lydiann’s blood nephew -- being the biological son of Lydiann’s (unwed) sister Sadie, who was then adopted by the Masts.
262* ''Literature/{{Pyramids}}'' by Creator/TerryPratchett features a pair of romantically inclined half-siblings who eventually figure it out (before getting seriously involved). This one might be a ShoutOut to ''Franchise/StarWars'', as the non-related male love interest is a LovableRogue smuggler with a CoolShip. (Also there's a bit of a twist, what with them being royalty in {{Fantasy Counterpart|Culture}} Egypt, where royalty traditionally marry relatives, so the Morpork-educated brother is probably the only person in the kingdom who has a problem with it.)
263* Played with in ''The Real Thing'' by Catherine Alliott. Protagonist Tessa has never forgotten her high school sweetheart Patrick, whom her father had forced her to break up with. In the present day her father reveals that he had an affair with Patrick's mother, and Patrick is Tessa's half-brother. Tessa believes her husband's cheating on her, and figures she could start a new life with Patrick - since they've already had a sexual relationship, and her father is too ashamed to tell anyone the truth. [[spoiler:Only for her mother to reveal she had an affair as well, and someone else is Tessa's biological father. Tessa's not related to Patrick, although she does have another half-brother, who she knows and ''also'' almost slept with.]]
264* In ''Remember Me'', by Christopher Pike, Shari's brother, Jim, is dating a girl named Amanda. It turns out that in fact Jim and Amanda are brother and sister.
265* In ''Repeat It Today With Tears'' by Anne Peile, the rather disturbed Susie begins an affair with her own father, who abandoned his family when she was a baby. He believes his ex and their children are living in Australia, and Susie gives him a completely fake account of her life so he will never find out. Immediately after he learns the truth [[spoiler:he's killed in a vigilante murder by Susie's stepfather, who refuses to believe he knew nothing about it.]]
266* In the novel ''The Shadow of the Wind'', Julian, an illegitimate child who doesn't know who his father is, has a secret relationship with [[spoiler:Penelope, the daughter of a rich man who mysteriously decided to take Julian in and pay for his education]]. It is, however, not until years later, [[spoiler:long after Penelope has died giving birth to Julian's child]], that he learns that she was actually his half-sister.
267* In ''Literature/SherlockInLove'', Literature/SherlockHolmes finds himself falling in love with the astoundingly intelligent and musically-gifted Violet Sigerson. [[spoiler: And then finds out that she is his half-sister, due to his mother's marital unfaithfulness. Holmes eventually tries to pursue a relationship, but Violet will have none of it and [[FakingTheDead fakes her death]] to stop him forever.]]
268* In the Peter David novel ''Literature/SirAproposOfNothing'', the title character eventually falls in love with the princess he's guarding. But the morning after they've consummated their love...he finds a flame birthmark on her hip, which suspiciously looks like the one on his. [[spoiler: Further, it's revealed (though to Apropos only) that the princess is the illegitimate daughter of the Queen and the court jester... and that answers Apropos's question of who his father is, as his mother was raped by a gang of knights... and a shadowy figure that matches the description of the court jester.]]
269* Creator/JRRTolkien's ''Literature/TheSilmarillion'' includes the tale of Túrin Turambar (dealt with at greater length in ''Literature/TheChildrenOfHurin''), whose sister Niënor was born after he left the family, causing them not to meet until she, having gone to look for him, has had her memory erased by the dragon Glaurung. Therefore, not knowing who she is, they get married and she even gets pregnant, but then Glaurung spitefully restores her memory in his dying moments, and she promptly commits suicide. Túrin does the same shortly afterwards. [[WholePlotReference Based on the story]] of Kullervo in ''Literature/TheKalevala''.
270* In Juliet Marillier's novel ''Literature/SonOfTheShadows'', the protagonists' sister, Niamh, falls for a druid. When her family finds out, they marry her off in a strategic alliance without telling her that the reason they're so horrified is that [[spoiler: the druid (Ciaran) is actually the son of her mother's evil stepmother, thus making him her half-uncle. Oops]].
271** Their relationship is later vindicated though. Their [[spoiler: daughter]] turns out to be [[spoiler: the child of the prophecy, ending a longstanding feud with Britain over sacred ground]]. Unfortunately, [[spoiler: Niamh never lived to see this, having been pushed off a cliff by the aforementioned evil stepmother when the child was a toddler]].
272** When you look at their family tree, Liadan and [[spoiler: Bran/The Chief]] are second cousins.
273* ''Literature/ASongOfIceAndFire'':
274** Theon Greyjoy's [[SheIsAllGrownUp unrecognized]] tomboy sister practically seduces him until TheReveal to purposefully mess with his head, and see what kind of man he's grown into during their separation.
275** Almost used later when Gendry, [[DisappearedDad who has no clue that his father is King Robert]], meets a whore named Bella who flirts with him, all the while bragging that she's the king's bastard. Part of her argument is that she has his famous black hair. Arya ([[IfOnlyYouKnew who does not know the truth either]]) argues that Gendry has it, too, so it's not like it means much. Fortunately for everyone, Gendry's really not in the mood.
276* In Creator/OrsonScottCard's ''Literature/SpeakerForTheDead'', Miro discovers his mom was cheating on his (sterile) dad with her old flame Libo, which makes him and his girlfriend half-siblings. Miro doesn't care, but the girl does. Tragedy ensues.
277* Josephine Angelini's ''Starcrossed'' series plays with this trope twice:
278** Helen is kidnapped by [[spoiler: her MissingMom]] who tells her that [[spoiler: Lucas, her main love interest, is her first cousin]]. In the next chapter, it's revealed that it's not true, but they spend most of the rest of the books thinking it's true.
279** Orion takes Helen to see his parents so he can explain his past better, and when they look in the house she sees his dad...[[spoiler:and her mom]]. Just as she starts freaking out, Orion quickly explains that it wasn't what it looked like and [[spoiler: Helen's mom helps his dad take care of Orion's mom sometimes.]]
280* Happens not once, but ''twice'' in ''Literature/TheStoneDanceOfTheChameleon''. Carnelian and Osidian meet in secret and have a passionate affair. Then it turns out that [[spoiler: Osidian is the GodEmperor's son, making them [[KissingCousins cousins]], since Carnelian's mother is the emperor's sister. Later, though, it turns out that Carnelian's father is actually [[BrotherSisterIncest the emperor himself]] -- which is not atypical in the ruling house, Osidian's mother being the emperor's other sister. Making them, you know, [[SiblingIncest brothers]].]] In case you hadn't noticed, this is [[RoyallyScrewedUp one messed up family.]]
281* ''Literature/SwordArtOnline'': In the ''Alfheim Online'' arc, Suguha Kirigaya, as her toon "Leafa", meets a newbie named Kirito (the main protagonist) and develops a crush on him. She doesn't realize until late in the storyline that Kirito is her live-in cousin Kazuto, and logs out immediately in shock, only coming back when Kirito asks her for her help rescuing his girlfriend Asuna, who was TrappedInTVLand by the ArcVillain.
282* In the ''Literature/TalesOfTheFiveHundredKingdoms'' series, the Tradition (a magic force that makes people's lives follow fairytale plots) will allow BrotherSisterIncest only if it's this. If the relatives know each other, they won't be compelled to fall in love even if it suits another Traditional path (e.g. RescueRomance).
283* In ''Literature/ThievesWorld'' badasses Tempus and Cime seem to be laboring under various curses related to this (or effects of mitigators). It seems to have driven them both AxCrazy, though in different ways. Some early stories danced around whether they really were related, but Janet Morris' ''A Man and His God'' confirmed it.
284[[/folder]]
285
286[[folder:Live-Action TV]]
287* A common PlotTwist in {{soap opera}}s is that some couple finds out that they are somehow related. And by common, we mean ''super common''.
288* Hispanic soap operas used to ''love'' this so much, but it has faded in recent years.
289** The ultimate parody of how this used to be done is the song "''[[http://www.planetadeletras.com/index.php?m=s&lid=77646 María Teresa y Danilo]]''", where a girl, daughter of the aforementioned characters, is forced to cancel her wedding after discovering that her fiancé is the son of her father... only for it to be revealed by her mother that, in fact, she is not his biological daughter.
290** Subverted in one memorable Argentinian case: the main characters find out they're siblings and go their separate ways. As usual, it turns out to be a lie. Only it's actually true... and their father has decided not to tell them. They marry and live happily ever after.
291----
292* In the ''Series/ThirtyRock'' episode "The Head and the Hair", Liz and the Hair find out right before kissing that their grandparents are cousins. He seems a little more comfortable with it than she is:
293-->'''Liz''': Okay, on the count of three, say what level of cousins we would have to be for this to be okay. One, two, three.\
294'''The Hair''': Fifth.\
295'''Liz''': Unacceptable, no matter what.
296* ''Series/Accused2023'': In "Jessie's Story" it turns out this Kara was so resistant to Jessie and Will growing close, as he's actually her half-brother. Kara obviously feared the two of them might have sex while unaware about this.
297* ''Series/TheAffair'': Thankfully it doesn't get that far, but when Noah finds himself at APartyAlsoKnownAsAnOrgy thrown by a Hollywood producer, he checks out a TwoPersonPoolParty before realizing that one of the two kissing girls is his daughter Whitney. He quickly makes himself scarce.
298* The 2019 Fox series ''Series/AlmostFamily'' has Julia Bechley rocked to discover her father, renowned fertility doctor Leon, has been using his own sperm to impregnate possibly hundreds of patients over the years. Julia is stunned when a guy she'd had a one-night stand with shows up as his parents had used the clinic, meaning she might have slept with her own brother. Thankfully, he's not although the fact he's married is still a dealbreaker for Julia.
299** Julia brings up to Leon how there's still the chance this could have happened to other people. To her horror, her father just brushes it off as "crossbreeding was a possibility I dismissed" to continue his work and even thinks it would be no big deal.
300* [[spoiler: Zig-zagged]] on ''Series/ArrestedDevelopment''; Maeby has an on/off relationship with [[spoiler:Steve Holt]], who is ultimately revealed to be [[spoiler:her uncle GOB's illegitimate son (played straight)]]. This prompts the couple to break up, but it turns out that [[spoiler: Maeby's mother Lindsay was adopted, meaning Maeby isn't related to Steve after all (subverted), or indeed her other cousin George Michael, who had been attracted to her since the pilot (Inverted)]]. An adult eventually finds out, however, and decides that regardless of who is related to whom the whole thing is just too weird. [[spoiler:Zig-zagged again in the GrandFinale, when it's revealed that while Lindsay is also the much younger half-sister of George Michael's grandmother Lucille, meaning George Michael and Steve Holt are half-cousins once removed to Maeby]].
301* ''Series/{{Arrow}}'': Early scenes suggesting a possible spark between Tommy Merlyn and Thea Queen become squicky in hindsight after the Season 2 reveal that they are half-siblings, sharing the same father. Thea had made a pass at Tommy which he rejected because [[{{Foreshadowing}} she was like a kid sister to him]]; when she learns (after Tommy's death) about her true parentage, Thea is understandably freaked out.
302-->'''Thea:''' ''(to Oliver)'' You're only my half-brother. You know who else was my half-brother? Tommy. Tommy who I tried to kiss. I tried to kiss my half-brother, who got killed by my real father. That's how screwed up I am!
303* ''Series/AsTheWorldTurns'': Holden and Lily are one of the show's biggest supercouples. Lily is also the biological daughter of Holden's sister Iva. Who fortunately turned out to be adopted herself so it was not incest after all.
304* In a Season 5 episode of ''Series/TheATeam'', "Family Reunion," [[HandsomeLech Face]] helps an attractive woman come to terms with her fugitive father reentering her life. Afterwards, he tells Murdock that he's going to ask her out after their mission is over because he's never met anyone else he's "felt so at ease with." Murdock starts insisting that she's not Face's type because he and the audience both know, due to dramatic irony, that [[spoiler: this beautiful woman is actually his half-sister, and her fugitive father is also his]].
305* A subtle one occurs in the relaunch of ''Series/{{Battlestar Galactica|2003}}'' where [[spoiler: Ellen Tigh sleeps with Cavil to free Saul. As it turned out, Ellen was one of the Final Five and was essentially Cavil's mother]]. It was a double-whammy, too. Not only had [[spoiler: Ellen viewed Cavil as a son, he was also designed to look like her father. Just another sign of how deep his misanthropy and hatred toward his "parents" really ran]]. And while [[spoiler: Ellen was unaware of this due to amnesia, Cavil knew all about it and deliberately set it up.]]
306* ''Series/BoredToDeath'': [[spoiler: Jonathon and his girlfriend find out they're half-siblings]]. Left unresolved due to cancellation.
307* Series/BostonLegal: In "The Bad Seed" a young couple know both their mothers went to the same sperm bank years prior and they are the result. They don't know if their mothers used the same donor or not, and it takes going to the lawyers of Crane, Poole, and Schmit to petition a judge to make the bank release just this information. The judge agrees with the claimants need for this information and orders the bank to release just the files on their mothers. [[spoiler:Both are shocked to learn they are in deed half-siblings]].
308* ''Series/BoyMeetsWorld'':
309** In one episode, Eric hooks up with a girl at a [[ItMakesSenseInContext combined school rave/parents' anniversary party]] who turns out to be his cousin. While they didn't get anywhere, he's still thoroughly squicked at the situation.
310** In a more minor example, both Cory and Eric leer at an old picture in their parents' photo album of a sexy young woman in a skimpy wet outfit, only to freak out when they realize it's their own mother.
311* In the ''Series/BurkesLaw'' episode "Who Killed the King of the Country Club?" had the killer trying to avoid this. A new member of the club turns out to have been killed by an elderly woman whose daughter had started dating the man. When the horrified daughter asks why her mother did this as "I loved that man!" her mother reveals "that man was your father!" 25 years earlier, she'd had a one-night stand with a plumber just a month before her wedding. She was thus able to pass off the child as her husband's. As fate had it, the plumber ended up becoming a millionaire to join the club and the woman was terrified he would end up in bed with their daughter. Burke openly asks why she didn't just tell either the truth but the woman didn't want to ruin her own social status with the affair becoming public. She's led off as the daughter can't believe how close she came to bedding her own father.
312* ''Series/{{Carnivale}}'': All right, we'll be fair: [[spoiler: Justin Crowe]] wasn't actually ''aware'' that he'd made creepy passes at ''two'' close female relatives. After all, [[spoiler: only his sister-lover actually knew that the new maid was Justin's illegitimate daughter]]. Not that that necessarily would have stopped him. At all.
313* ''Series/CarnivalRow'': [[spoiler: Jonah]] is shocked to learn [[spoiler: Sophie]] is his sister, as they share a father, after they've had sex. She already knew and didn't care, invoking her Pharaonic ancestry, since the Pharaohs often married their sisters. He comes around after this, and they stay together, with her even proposing they marry as well.
314* ''Series/CasoCerrado'': One case involves a woman who wants to divorce her husband after learning that he's her paternal grandfather. She was so ashamed that she tried to kill herself. Her grandfather is a musician with at least 26 kids, but he has been in the life of none of them.
315* In ''Series/ChampaignILL'', Alfonso meets a girl online after moving back to his hometown. They're surprised they have so much in common during the date. Meanwhile, Ronnie figures out she's his cousin and races to stop them from going all the way. He arrives too late. They keep doing it until Alf joins a sex addicts anonymous program.
316* In the sixth season of ''Series/{{Community}}'', minor character Garrett gets married to his girlfriend. It's only at the reception after the wedding that they realize Garrett's great aunt and his wife's grandmother are the same person, making them cousins. [[KissingCousins They decide to stay together anyway]].
317* The ''Series/CriminalMinds'' episode "Taboo" had an interesting take on this trope. [[spoiler: The unsub was adopted as a baby by a single mother with a biological teenage daughter. The daughter was hypersexual, thanks to a brain injury, and the boy grew up attracted to her, even spying on her as she had sex with his friends. When she takes him to a lover's lane for privacy, he gleefully makes his move, pointing out that they're NotBloodSiblings, so it's about time for him to get his turn. She then reveals the truth: she's not his sister, she's his ''mother.'' The boy snaps, blaming his "sister" and "mother" for turning him into an abomination.]]
318* This becomes a motive for murder on a case in ''Series/CSIMiami''. Dad had a SecretOtherFamily, son from Family A met up with daughter from Family B, fell in love, and had a baby together. Then son found out...
319* On ''Series/{{Dallas}}'', the writers revealed after a few seasons that the Ewings' farmhand Ray was Jock Ewing's illegitimate son, having forgotten that in the beginning of the series, he had been having an affair with Jock's granddaughter Lucy. After realizing what they'd done, they made sure to never reference the affair again, though it was never actually denied to have happened.
320* ''Series/Dark2017'':
321** Jonas finds out that he has been involved in this once he finds out the truth about his father's identity as the time-displaced-to-1986 Mikkel late in season one. However, the other party does not find the truth out until one season later, but this revelation does not stop the two from still having romantic feelings for each other... [[spoiler: at least before the older Jonas murders Martha in front of the younger Jonas [[StableTimeLoop to ensure his own timeline proceeds as happened]].]]
322** Season 2 reveals that [[spoiler: Charlotte's daughter, Elisabeth, is also her ''[[MyOwnGrampa mother]]'', meaning that their husbands, Peter and Hanno/Noah respectively, unknowingly married their own granddaughters.]]
323** Season 3 reveals [[spoiler: the same deal to be true of ''the entire Nielsen/Kahnwald line'', as Tronte Nielsen, Ulrich's father, was the son of [[NoNameGiven The Unknown]], the son of Martha (Ulrich's daughter) and Jonas (Ulrich's grandson, albeit not the [[AlternateSelf same]] [[AlternateUniverse Ulrich]]). Meaning ''their'' partners all married, or at least had a child with, their own great-great-grandsons, who are also their ''great''-great-great-grandsons, at least genetically. Oh, and Agnes and Noah's parents turn out to be Bartosz and Silja; Silja is Bartosz's half-great-aunt. Confused yet? [[RealityBreakingParadox So is the universe]].]]
324* ''Series/DaysOfOurLives'':
325** The show had a scene in which [[spoiler: Lucas almost has sex with Cassie. They are only stopped when Rex, Cassie's twin brother, arrives and tells them that they are half-siblings.]]
326** Before that, Cassie had a crush on and kissed her [[spoiler: cousin Shawn-Douglas]].
327** Long before that in ''Days'', Tony [=DiMera=] was in love with a woman named Renee. Unfortunately, it turned out they shared the same father, Stefano, but luckily it soon came out that Tony was really the son of the family's gardener, not Stefano (of course, since this was a soap by that point Renee had married another man...and then got killed by a serial killer...). For long-time fans, this caused a serious amount of squick when years later a retcon made Tony Stefano's biological son, but in the end another retcon made the Tony that had appeared since then his evil doppleganger Andre (long story, naturally) and showed that Tony wasn't Stefano's biological son after all.
328* In the ''Series/{{Dollhouse}}'' episode "Haunted", Echo gets imprinted with the personality of a wealthy woman who wants to attend her own funeral. The woman's son makes a pass at her; she's suitably disgusted.
329* [[https://www.youtube.com/watch?v=HEhExKVfNWg&ab_channel=krazoner This]] Dutch commercial telling kids not to engage in cybersex has two teens flashing each other over webcams before recognizing the shirts their partner was wearing on the opposite sibling at the breakfast table.
330* ''Series/Dynasty1981'': In an early season three episode, Fallon meets Adam at a bar and after some flirting, the two kiss. The following day, Alexis (Fallon's mother) informs her and Adam that they are siblings. Their relationship doesn't get any better from there.
331* ''Series/Dynasty2017'': For a while, Fallon hooks up with Jeff. It's later revealed that Jeff's mother, Dominique, is Blake's half-sister, meaning Fallon and Jeff are half-cousins.
332* In ''Series/EastEnders'', Kareena Ferreira dated family friend Tariq, later making the relationship incestuous when it's revealed Tariq is her half-brother; the family's father had an affair with Tariq's mother. Tariq knew the truth but thought that he could get closer to the family by dating Kareena, taking care to ensure the relationship never became sexual.
333* On the British soap ''Series/{{Emmerdale}}'' Maisie Wylde and Ryan Lamb are caught in bed together and are promptly informed (after many months of hiding this from them) that they are half-siblings. Which disgusts both of them and wind up sending Maisie into rehab and getting their father shot.
334* ''Series/{{Endeavour}}'': In "Trove", a man performing a DeadPersonImpersonation discovers he has just slept with his daughter. The girl had been an infant when he [[FakingTheDead faked his death]] and stole his commanding officer's identity. The girl had taken her stepfather's surname, so he had no idea who she was. This causes him to vomit.
335* ''Series/{{Endgame}}'': When the son of the Huxley Hotel's owner goes missing, it turns out that he's gone on a bender because he discovered that the girl he was planning to marry was really his half-sister because his father had had an affair with her mother. [[spoiler: Then it also turns out that his ''mother'' had been having an affair too, so his father wasn't really his father, and they were unrelated after all.]]
336* ''Series/{{ER}}'': A teenage girl is brought in to the E.R. after a fight breaks out at a Jerry Springer-esque daytime tv show. The poor girl had her mother drop one hefty bomb on her. According to the mom, the girl's boyfriend, who she'd been openly having sex with, is actually her half-brother. The girl is devastated because she loves him tremendously and had to be told the terrible news on live TV. Only after the girl [[spoiler: commits suicide by jumping off the roof of the hospital]] do we find out [[spoiler: the mother had lied and only said what she said because she wanted to be on television.]]
337* ''Series/FatherBrown'': "The Resurrectionists", a pair of lovers turn out to be cousins who never knew that their parents were siblings.
338* ''Series/FBIMostWanted'': In "[[Recap/FBIMostWantedS04E19 Bad Seed]]", husband and wife Miles and Savannah Maddox were horrified to learn from their DNA ancestry test kits that they are actually half-siblings after being married for three years. What's worse is they also learned that they were the product of their biological father, Dr. Gregory Scanlon, committing [[MedicalRapeAndImpregnate fertility fraud]] who knowingly passed down [[https://en.wikipedia.org/wiki/Lupus lupus]] to his offspring.
339* ''Series/TheFreshPrinceOfBelAir'':
340** In the episode, "That No Lady, That's My Cousin", Ashley starts dressing a bit more "mature" to fit in at school, and Carlton doesn’t even recognize her at first when she walks into the lunchroom and is promptly surrounded by boys.
341--->'''Carlton:''' Wow! Will, check out the talent! She’s cool! She’s hot! She’s...
342--->'''Will:''' YOUR BABY SISTER, MAN!
343--->'''Carlton:''' ... (ScreamsLikeALittleGirl)
344** In another episode, this time involving Carlton's ''older'' sister, he and Hillary both get into online dating back when it was in its infancy, meaning [[DatingServiceDisaster not everyone had photos attached to their profile]]. It's not until they both separately arrive at the restaurant that they realize that they've been flirting with each other this whole time.
345--->'''Hillary:''' ...Would you quiet down?
346--->'''Carlton:''' Quiet down? I'M ON A DATE WITH MY SISTER!
347--->*Everyone at the restaurant looks at them*
348--->'''Carlton:''' It's my favorite country-western song *embarrassed laugh*.
349* In ''Series/{{Friends}}'' Ross and Monica, who are siblings, kissed when both were drunk at a party. However, Monica was half-asleep on a bed and didn't know who that kiss was with, and Ross thought she was Rachel under a pile of coats as it was in a dark room. They only realized it was them years later.
350-->'''Ross:''' You were my first kiss with Rachel?\
351'''Monica:''' You were my first kiss ''ever''?\
352'''Chandler:''' What have I married into?
353* ''Series/FutureMan'': Josh almost has sex with his own ''mother'', having mistaken her for someone else. He finds this out ''just'' in time before they get that far.
354* ''Series/GameOfThrones'':
355** There's a somewhat squick-worthy one-sided example of this. In Episode 2 of Season 2, Theon Greyjoy returns to his homeland where he meets a young woman and they begin flirting. During a subsequent horseback ride, Theon begins feeling up the woman in a sexual manner (this is the series that led to the phrase "sexposition" being coined) and she not only doesn't object, she seems to take pleasure from it. A few minutes later, Theon (and the audience) get squicked when he learns that woman he was making out with was his ''sister'', Yara, whom he hasn't seen since she was a child, and that she was aware the entire time and played along mostly to see how he'd react in a SecretTestOfCharacter. Needless to say, he failed miserably.
356** As of Season 7, there is sexual tension developing between [[spoiler: Jon Snow and Daenerys Targaryen, and it stops being tension when they have sex in the season finale]]. However, unbeknownst to either of them they're [[spoiler: nephew and aunt despite being the same age, as Jon is actually the son of Dany's much older brother Rhaegar.]] In Season 8, when they find out, [[spoiler: Dany doesn't really care about the incest (coming from a dynasty and culture where [[BrotherSisterIncest marriage between siblings]] was a regular occurrence) and is more concerned that Jon's true heritage means he has a stronger claim to the Iron Throne than she does, as any legitimate child of Rhaegar would be ahead of her in the Targaryen line of succession. However, while Jon has sworn his undevoted allegiance to her and expresses no interest in disputing her claim, he is much more uncomfortable with their consanguinity, rebuffing Dany's romantic advances afterwards.]]
357* ''Series/TheNanny'' had an awkward relationship revealed at a wedding. Fran and a man were mutually flirting with each other and were thinking about dating. However, near the end of the episode, they both end up at a wedding of one of their relatives. Once there, Sylvia casually mentions that the two of them are closely related cousins. They are both mutually creeped out.
358* On ''Series/GreenWing'', Guy Secretan doesn't find out [[spoiler: Joanna]] is his long-lost and presumed-dead ''mother'' until after they've slept together. And it's been caught on tape.
359* On ''Series/GroundedForLife'', Lily made out with a guy at the funeral. She later learns he was her cousin. Then she is somewhat relieved when she learns he was a cousin by marriage but squicked again when learning they're cousins by his marriage.
360* Throughout ''Series/HenryDanger'', Piper adores Kid Danger and has a huge crush on him, unaware that he is actually her brother, Henry. Needless to say, when she finds out her brother and hero are the same person, she is horrified and disgusted.
361* ''Series/{{Hollyoaks}}''.
362** Rhys and Beth start dating only to discover they are half-brother and sister. Since everyone knows, they move on to new partners, but then decide to have an affair with each other. [[spoiler:It ends very badly when they get arrested and then Beth is killed in a car crash as they try to run.]]
363** Narrowly averted when Ste meets his estranged father Danny, and heavily flirts with him before finding out they are related.
364** Dodger turns out to be the father of his own twin sister's daughter - they had been separated as children, then met again and slept together as teenagers without being aware of each other's identity.
365* One episode of ''Series/{{House}}'' had a young married couple who both turned out to share the same rare genetic disease... because unknown to the couple, the man's father had slept with the woman's mother and they were half-siblings. On top of that, the half-brother wants to stay together; while the half-sister is disgusted. The episode ends without resolving the situation, leaving the brother/husband hoping that she'll come back while Foreman (who supports the relationship) keeps him company.
366* ''Series/HowIMetYourMother''
367** Robin and Barney were on their way to their wedding when they discovered they were related through a mutual cousin named Mitch. By the end of the episode, it's revealed that Robin at least is not blood-related to Mitch, so they manage to avert this trope. They did spend the entire episode awkwardly avoiding any sort of contact though.
368** In an earlier episode, Barney is [[MatingDance flirt-dancing]] with a girl in a disco. But he is only seeing her from behind, and she can't obviously see him at all in this position. Then she finally turns around - and Barney is recognizing his cousin. Quite disturbed, he tells Ted that [[LetUsNeverSpeakOfThisAgain they must never speak of this again]], not even in the form of a [[NoodleIncident funny "Do you remember that time when..."-style anecdote]].
369* ''Series/InspectorGeorgeGently'': "Gently Going Under" features a half-siblings version. The girl's father had an affair with the boy's mother while her husband was away at the war. When the relationship is discovered, the father tries to move away and take the daughter with him but she is already pregnant. The boy's mother tells her the truth, causing her to attempt to abort the child.
370* ''Series/JustShootMe'':
371** Jack's handsome new ex-marine trainer keeps trying to ask Nina out. Nina, who usually ReallyGetsAround, keeps refusing, much to her surprise. It is at episode's end that she discovers why she's not attracted to him: they're cousins.
372** In another episode an old female friend of Jack's shows up with her son, and he and Maya show signs of being interested in each other. Jack, however, is horrified, because he had a one-night stand right before her wedding and the timing would line up with him being the young man's father. Eventually she reveals that she secretly got a sample of Jack's DNA years ago and tested it, showing he's not the father. By this point, though, Nina's broken the news to the would-be couple, and the man is horrified, so he breaks up with Maya.
373** Jack has Elliot, the magazine's head photographer, take his daughter Maya's new driver's license photograph. The UST between the two leads to a gorgeous photo, which Jack later sees and, not realizing, comments on the beauty of the woman in it. When reminded of his request, Jack takes it well.
374-->'''Jack:''' [Nonchalantly] I'm going to go [[Theatre/OedipusRex put out my eyes.]]
375* ''Franchise/KamenRider'':
376** ''Series/KamenRiderDouble'': [[spoiler:Phillip]] is really the brother of [[spoiler:Wakana]] but doesn't know it at the time. He's close to her and plans to leave town with her. Then it turns out that she's really his sister. Once the reveal is made there's no change in plans or attitudes at all (although things change for other reasons) and the audience is apparently supposed to accept that "I care for this girl I know" and "I care for my sister" were exactly the same thing all along. There isn't even a {{lampshad|eHanging}}ing. Although, to be fair, he never really seemed to think of her that way.
377** ''Series/KamenRiderDenO'' likewise [[ShipSinking sank the ship]] of [[spoiler:Ryotaro/Hana]][[note]]which already took a massive hit when [[spoiler:Hana was [[FountainOfYouth de-aged to childhood]]]][[/note]] by revealing that the latter was the former's [[spoiler:Niece]] [[KidFromTheFuture from the Future]]. Thanks, TimeTravel! They still got off better than the [[spoiler:[[ParentalIncest Yuuto/Hana]]]] shippers, though.
378** ''Series/KamenRiderKabuto'' has plenty of ShipTease for Tendou and Hiyori earlier in the series (with a guest actor who'd played Tendou as a child [[WordOfGod stating in an interview]] that he'd been led to believe Hiyori was Tendou's love interest.) However, Hiyori turns out to be [[spoiler: a Worm that has copied itself from Tendou's sister]], making them siblings. Subsequently, the show dropped any potential romantic arc between them and began having Kagami pursue her instead.
379** ''Series/KamenRiderAmazons'' has Mizuki, who is initially presented as Haruka's foster sister, as his love interest in the first season. It's then revealed that [[spoiler:they are genetic half-siblings because Mizuki's mother used her own DNA to create Haruka.]] The second season subsequently abandons the romantic angle.
380* This is [[PlayingWithATrope played with]] in Season Eight of ''Series/KnotsLanding''. Towards the end of the season, Anne tells Mack that Greg, not him, is Paige's father. Karen and Mack are concerned that Paige may unwittingly be having an incestuous relationship with her uncle as she was dating Greg's half-brother Peter Hollister at the time. It turns out that they need not have worried since Anne was merely being vindictive and Mack is indeed Paige's father. Greg and Anne never had sex, though it wasn't because of any lack of trying on Greg's part. Besides which, even if Greg had been her father, it still wouldn't have been incest since Peter wasn't actually Greg's half-brother, something which the audience knew but Karen and Mack didn't.
381* ''Series/LadyDynamite'' has Maria dating a black boy during one of the Duluth scenes. Her dad is against it, so she gives him a speech about the evils of racism - that's when he explains that, during his youth, he slept with the boy's mother during a key party, and might be the boy's biological father.
382* ''Series/LawAndOrderSpecialVictimsUnit'':
383** Occurred in at least one plotline. The girl was the product of her mother's affair with the boy's father, and when the two began dating due to accidental reverse psychology (the mothers hated each other - the father was in fact the husband of both and living a double-life, known about by one of the wives the whole time), the girl is accidentally killed by her father when he reveals to her that he is the boy's father too. The autopsy reveals that the girl was pregnant when she died and that the boy was the father and that he was related to her. The boy is horrified and vomits in Stabler's office. The boy's mother kills his father when she finds out that he was planning on leaving her for the girl's mother, who was jailed for her part in the myriad crimes going around and with whom he also has a son, the boy's half-brother, and leaving the two new half-brothers without any parent not in prison.
384** A truly dark example in season 19's "Send In the Clowns." A teen goes missing in New York and a butcher is accused of the crime. It turns out she's been having an affair with her music teacher who hailed her genius at the piano. The cops bring them both in as the girl's mother slaps the teacher and starts ranting about his seduction methods with obvious first-hand knowledge. She confesses to her husband she had a one-night stand with the guy...17 years ago. "Do the math." The man himself is utterly horrified and nearly throttled by the husband, and it's reported he's on suicide watch. His daughter's reaction? She's ''happy'' because she now knows her father is a musical genius, not "a garbage man", and Benson realizes the girl is deeply troubled.
385* In ''Series/LegendsOfTomorrow'', after many time traveling adventures, Martin Stein's memories start gradually changing (mostly incoherent) and he repeatedly sees visions of a beautiful woman who isn't his wife. At first, he sadly assumes that changes to history caused him to get together with a different woman. When he finally meets her in the present, it turns out the woman is his daughter (he didn't have any children before history changed).
386* The end of the episode with the Pimp Hat in ''Series/LessThanPerfect'' had Owen and his DistaffCounterpart date reveal that one of the many things they had in common was that they both had donor dads who were artists. Claude pulls him aside to tell him that it was very likely they were brother and sister. He retorts that "this couldn't wait until tomorrow?", meaning he wasn't completely against the incest.
387* In ''Series/{{Lewis}}'' Brother and Sister twins that were adopted by different families meet, fall in love, and marry. When they can't have kids, the couple gets genetic tests done. They find out not only that they are related, but they both have the markers for Fatal Familia Insomnia. They track down their birth mother but get Dr. Dobson's name because their mom used it. They are slowly going insane from lack of sleep.
388* ''Series/LostGirl'':
389** Bo gets hit on and kissed by a woman who turns out to be her long-lost mother Aife (Bo and her mother are succubi and don't age).
390** Later in the show, Bo meets and has sex with Persephone, wife of Hades, only to learn after the fact that [[spoiler:Hades is her biological father, thus making Persephone her stepmother]].
391* In one episode of ''Series/TheLoveBoat'', a woman comes on board with her son, to meet the daughter she gave up for adoption. Before they all get together, the son and the daughter meet, and, not knowing who the other is, they fall in love and have sex. The daughter is freaked out when she meets the mother and discovers who the guy she slept with is. Fortunately the son is actually the mother's step-son, so the couple aren't blood siblings and can get married, but the mother has no idea how she'll phrase the wedding invitations.
392* On Creator/{{MTV}}'s late-night, sex-advice talk show ''Loveline'', a man called in asking what to do after discovering his pregnant girlfriend is his half-sister (his mother was estranged for years and the girl was racially-mixed, so he had no idea at first).
393* In one episode of ''Series/MalcolmInTheMiddle'', Reese finds Lois's high school diary, thinking it belongs to a schoolmate he's never met. After reading it he develops a crush on the mysterious girl, until Lois sees him with it at the end of the episode. Needless to say his fantasy of kissing her goes in a different direction.
394* A ''Series/MadTV'' sketch parodying {{Korean Drama}}s ends with the main character and his love interest learning they share the same mother.
395* In the season 2 finale of ''Series/MarriedWithChildren'', Kelly learns everyone in her mother's hometown is related, even a guy she had sex with. Her response is immediate BrainBleach.
396* ''Series/TheMick'': Chip meets his biological father after learning about him, and finds that his half-sister is attracted to him. She kisses him, although Chip tries to resist this, and he stops things after she does. [[spoiler:{{Subverted}} though later when it turns out they don't share a father.]]
397* ''Series/MidsomerMurders'':
398** In one episode, a man had 'spread his seed far and wide'--you could hardly turn a corner without finding one of his bastards. One couple didn't meet until they were both in graduate school in Canada and got married, only later realizing they were half-siblings; she was squicked, he didn't mind. It's also been used in several other episodes.
399** In one, a woman learns the younger employee she's been sleeping with is actually her nephew and is violently sick. Said young man doesn't react as much, because he's still under the shock of learning that he's the product of BrotherSisterIncest.
400** Inverted in "[[Recap/MidsomerMurdersS12E6 The Creeper]]" where two childhood friends clearly like each other, but don't act on it because they believe they're half-siblings. (His parents were having trouble conceiving, and her father agreed to sleep with his mother to get her pregnant, but his mother's husband -- who was okay with this -- would be the father legally speaking. The kids were told when they were old enough to understand.) The investigation of that episode's murder leads to the revelation that his mother was ''also'' having an affair behind both men's backs, and her paramour was actually the kid's real father. Both friends are stunned, but admit they're sort of relieved they're not related after all, and the last scene heavily implies they've hooked up.
401** "[[Recap/MidsomerMurdersS13E5 Master Class]]" has a young woman almost hook up with a much-older man who is not only her father, but also her ''[[ParentalIncest grandfather]]'', and he sought her out ''on purpose''. (It turns out to be part of some crazy eugenics scheme on his part.) Fortunately, Barnaby reaches her and informs her before anything happens.
402* In ''Series/MrRobot'', Elliot's fellow hacker Darlene is unusually close to him. She knows where he lives, seems to have little boundaries with him, and is unusually concerned about his safety for someone he barely knows. When one of their hacks is successful and Darlene congratulates him and tells him she "loves [him] so much", [[spoiler: Elliot kisses her, which causes her immediate disgust and she asks if he's forgotten who she is. Turns out, she's his sister and Elliot, who has a number of mental issues, has forgotten this.]]
403* In ''Series/MurderSheWrote: The Celtic Riddle'', [[spoiler: it's never actually spelled out, but it seems likely that the reason Eammon was a benefactor to Paddy was that he suspected Paddy might be the long-lost son he wanted to make things up to, and this is also why he disaproved of Paddy dating his daughter. Luckily it's subverted, as the "Lost Boy" turns out to be someone else.]]
404* Referenced in ''Series/MyNameIsEarl''. Joy never told her parents that she divorced Earl and married Darnell because she believes her father is a racist since he wouldn’t let her date a Black boy in high school. It’s later revealed that he had [[RaceFetish numerous affairs]] with Black women throughout the years, and don’t want her dating that boy because he was probably her half-brother.
405* In ''Series/TheNanny'', Fran finally meets [[Creator/JonStewart a guy]] who seems absolutely perfect for her: Jewish, a doctor, and understands her. At Fran's cousin's wedding, they see each other, and kiss. Cue Fran's mother...
406-->'''Sylvia:''' Isn't that adorable. Let me get a picture of you and your cousin Bob. \
407''(Fran and said cousin immediately jump apart, looking thoroughly {{Squick}}ed)''
408* ''Series/{{NCIS}}'' season 6 episode "Heartland" had the team go to the mining town of Stillwater (coincidentally Gibbs' birthplace) where it was revealed the hospitalized Marine and his childhood friend, who remained in Stillwater waiting for him, shared the same father unbeknownst to them both. Though she maintains that their relationship was strictly platonic, they did have feelings for one another.
409* Defied in ''Series/NewAmsterdam2008''. The immortal protagonist John, who ''is'' very much capable of [[ImmortalProcreationClause having children by mortal women]], keeps track of his family tree specifically so he can avoid getting into a relationship with someone who might turn out to be related to him.
410* Averted in ''Series/TheNewMikeHammer''. Mike meets an attractive woman with the [[ThePornomancer assumed inevitable bedding]]. However she tells Mike that before he takes her upstairs he needs to know something. Mike however has already realised she's a daughter he never knew he had.
411* ''Series/NipTuck'': In season 5, Christian finds out that he fathered a daughter when he was in college. She just happens to be Matt's new girlfriend (who was raised as Sean's son, but is actually Christian's).
412* ''Series/TheOuterLimits1995'': In "[[Recap/TheOuterLimits1995S3E4LastSupper Last Supper]]", Frank worries that Jade is his daughter, since he had sex with Laura, who he's sure has to be her mother due to their resemblance, around the time she would have been conceived. She's in a relationship with his son from another woman, so he's afraid the trope is in play. However, it turns out that Laura and Jade [[ReallySevenHundredYearsOld are really the same woman]].
413* On ''Series/TheOutpost'', Janzo has spent most of the second season bantering and flirting with handmaiden Naya. They finally share kisses while locked in a cell alongside Jazo's mother, the Mistress. Naya tells of her mother and as soon as she hears the name, the Mistress starts laughing "know her? I sold you to her!" She then spells out how Janzo has just been making out with his ''twin sister''. Poor Janzo nearly has a full breakdown and Naya isn't much better.
414* ''Series/RedDwarf'':
415** It was revealed that Lister's ex-girlfriend Kochanski is actually his mother. In the next series, Lister still uses a [[LovePotion sexual-magnetism virus]] to seduce her in an elevator despite his knowledge of this and it nearly works. Then again, Lister also discovered at the same time that [[MyOwnGrampa he was his own father]] (via in-vitro fertilization), which probably trumps any genetic relationship concerns.
416** Anticipated by Rimmer in "Back To Earth"; After telling the creator to create for him a beautiful, adoring girlfriend, he quickly adds that she should NOT turn out to be his long-lost sister.
417** The novelization ''Better Than Life'' has Rimmer's second wife turn out to be [[spoiler:based on a younger version of his mother]]. He can't even complete the thought when he realizes it, he's too disgusted and horrified.
418* ''Series/{{Riverdale}}'': Some time after Jason Blossom was murdered, Polly Cooper reveals she had been sleeping with him and is pregnant. Her father Hal goes nuts and demands she get an abortion. The rest of the family assumes this is because the Blossoms and Coopers are FeudingFamilies, but Hal reveals that his grandfather was the brother of Jason's great-grandfather, but estranged from the Blossom family and changed his last name to Cooper, which is what started the feud in the first place. This means that Polly and Jason are third cousins. Polly decides she doesn't care and will carry the pregnancy to term.
419* In ''Series/{{Scrubs}}'' when JD's girlfriend gets pregnant, they discuss the situation and JD is opposed to adoption because he fears this trope may occur if they have a daughter.
420* On ''Series/{{Shadowhunters}}'', after an entire season of flirting, kissing, and overall developing strong romantic feelings for one another, Jace and Clary find out they are actually brother and sister in the episode "Blood Calls To Blood", from the mouth of Clary's father [[BigBad Valentine]] (later confirmed by Clary's mother). [[spoiler:[[SubvertedTrope Actually, Valentine lied]]: Jace is the child of a different pair of Shadowhunters altogether, whom Valentine raised to compare with Clary's ''actual'' biological brother Jonathan (and telling Mom that Jace ''was'' Jonathan). On those grounds, Jace and Clary resume their relationship late in season two.]]
421* On ''Series/{{Smallville}}'', when Clark meets Kara (aka Comicbook/{{Supergirl}}), they seemed a little attracted to each other. When Kara's comment about her father Zor-El causes Clark to realize that they are cousins, he backs up, clearly (and understandably) disappointed.
422* In season 3 of ''Series/SonsOfAnarchy'' it is revealed that Jax Teller and Trinity Ashbey are both John Teller's children. Ony a few people know of this and since Jax lives in California and Trinity in Northern Ireland they do not see the need to tell them. When Jax comes to Ireland he and Trinity quickly hit it off and are about to have sex when their mothers walk in on them.
423* One episode of ''Series/{{Superstore}}'' plays this as a joke when Justine and Marcus discover they share a cousin, then quickly realize they should stop hooking up (which was also a reveal).
424* ''Series/{{Taskmaster}}'': in the barrage of [[{{Narm}} Narmy]] tropes engendered by the "[[SoapWithinAShow most suspenseful soap opera cliffhanger]]" task in "A Coquettish Fascinator," Jess and Kerry build this into their entry, "Cul-de-Sac":
425-->'''Kerry:''' He's the best I ever 'ad, Donna!\
426'''Jess:''' ''(dramatic inhaler puff)'' You can't be with him, [[PlayingWith/OneSteveLimit Donna]]!\
427'''Kerry:''' Why?!\
428'''Jess:''' 'Cause you're his mum!\
429''([[SoapOperaOrganScore melodramatic organ music]], [[VomitIndiscretionShot Kerry pukes]])''
430* An unusual example in ''Series/TrueBlood'': Vampire Bill, turned in the 1800's, finds out his human squeeze Portia Bellefleur and other members of the Bellefleur family (recurring characters in the series) are descended from his human daughter, and are thus ''his'' descendants. Bill is far more grossed out by this than Portia. She is perfectly willing to continue their sexual relationship, citing logical reasons why this shouldn't affect them: they're consenting adults, vampires ([[OurVampiresAreDifferent in this setting]]) can't produce children, and even if they could, Bill and Portia are as genetically similar as perfect strangers. Nonetheless, Bill is simply too uncomfortable to continue a relationship with his great-great-great granddaughter, so he [[MoreThanMindControl glamours]] her into being utterly terrified of him just so she will leave him alone. The one upside is that Bill develops an OddFriendship with Portia's brother, Sheriff Andy, due to his ability to act on Bill's legal behalf as his living heir, with the bonus that Andy isn't trying to sleep with him.
431* ''Series/TwoAndAHalfMen'': After talking to Charlie's latest piece of ass Gloria, Evelyn goes out of her way to stop her and Charlie from sleeping together. Right before they're about to do the deed, Evelyn brings over Gloria's mother and they explain that they each slept with the other's husband shortly before the mother got pregnant, and that there's a chance that Gloria and Charlie are half-siblings. This puts Charlie off, but Gloria ''still wants to screw him.''
432* ''Series/TheUntamed'': Like in [[Literature/GrandmasterOfDemonicCultivationMoDaoZuShi the novel]], Jin Guangyao and Qin Su get engaged before either knows they're half-siblings. Unlike in the novel, Qin Su isn't pregnant before the wedding. Her mother still tells Jin Guangyao the truth... and then he marries her anyway. And has sex with her when he knows she's his sister. Qin Su only finds out years later, and she's so horrified she kills herself.
433* In ''Series/VeronicaMars'', Duncan Kane broke up with Veronica because his mother told him she was his half-sister. After the first season finale revealed Veronica and Duncan weren't related, they got back together (until Duncan got PutOnABus).
434* In ''Series/WaywardPines'', Jason Higgins finds out that the woman he has been having a relationship with, Kerry Campbell, is actually his mother. The two lovers are around the same age because [[spoiler: Kerry was unfrozen many years after Jason]].
435* The Korean soap opera ''Series/WinterSonata'' is ''Series/MarmaladeBoy'' if Yuu went missing, got amnesia, and [[spoiler: really is half-siblings with his love interest. Well, in fact he could be instead the half-sibling of his love ''rival'', but the soap just was happy toying with that until the last chapter]].
436** There is a memorable scene in this drama where one of the rivals, after being clued of the above situation and arguably tired for the on-off situation who has already left her out of the game, ends yelling to one part of the conflicted couple "It doesn't matter if you are really siblings or not, just go out of the country and marry anyway! Abroad nobody is going to know!".
437
438[[/folder]]
439
440[[folder:Music]]
441* ''Music/TheMerryWivesOfWindsor'': "[[https://www.youtube.com/watch?v=XDs74OoIKcU All the Lads in Town]]" is about a girl who discovers that her father's roving ways have resulted in her suitor -- and, in fact, every eligible lad in her town -- being her half-brother. She despairs that she'll be forced to remain an unwilling maiden all her life, but at the end her mother tells her that she was actually fathered by a passing sailor and as such is free to bed who she will.
442* Music/{{Sia}}: The song "Butterflies" plays this on the listeners. It sounds like just a regular song about lingering awkwardness in a relationship, until the very last line right at the end of the song, when she casually remarks "Because we came from the same cocoon".
443* Music/WeirdAlYankovic: The second verse of "A Complicated Song" provides the page quote. After discovering his girlfriend is his cousin, the narrator wonders if he should still stay with her, have inbred kids with 11 toes, and "[[DeepSouth move to Alabama where that kind of thing is tolerated]]".
444-->I was feelin' pretty down\
445'Til my girlfriend came around\
446[[FiveSecondForeshadowing We're just so alike in every way]]\
447I gotta say\
448\
449In fact, I just thought I might\
450Pop the question there that night\
451I was kissing her so tenderly\
452But woe is me\
453\
454For who would have guessed\
455Her family crest\
456I'd suddenly spy\
457Tattooed on her thigh?\
458And son of a gun\
459It's just like the one\
460On me
461
462* Gothic Americana might not exist as a genre without this trope. Slim Cesna's Auto Club has an EP named "Crossbreeding Begins at Home." Similarly, about half of Jay Munly's oeuvre seems to rely upon this trope. If you're curious, look up the lyrics to "Big Black Bull Comes Like a Caesar" and "There's a Goose Walking Over My Grave."
463* In the folk song "I'm My Own Grandpa," the narrator marries an older woman with an adult daughter. The narrator's father then marries the daughter, making the son's stepdaughter his stepmother. Because the narrator is married to his stepmother's mother, he has become his own step-grandfather. Not actually incest, either.
464** A real life example was avoided when Mandy Smith's mother broke up with Rolling Stone Bill Wyman's son. Smith and Wyman were married at the time, giving Smith a narrow escape from becoming her own step-granddaughter-in-law.
465* Cornelis Vreeswijk's ''[[https://www.youtube.com/watch?v=J_JJaay6i_c Incestvisan]]'' (Incest Song) has a similar structure an example named above: Boy meets girls, falls in love. Dad intervenes, claiming they are his sisters. Boy then talks to mom, mom: "Oh, don't worry, he's probably right but he's not YOUR father anyway..."
466* The folk song "[[http://www.lyricsdownload.com/sainte-marie-buffy-johnny-be-fair-lyrics.html Johnny Be Fair]]" parodies this. The female narrator repeatedly falls in love with men, only for her father to pull out the ParentalMarriageVeto because he's ''their'' father too. In the end, she goes to her mother, who says "he's not really your father, marry anyone you want". It dates back to Elizabethan times and probably further.
467* Frank Zappa's "Magdalena" is a lengthy and detailed confessional by a Canadian maple syrup salesman to his teen-age daughter of what he'd like to do to her.
468** There's also "Brown Shoes Don't Make It", with this exchange, repeated three times:
469--->'''Man''': If she were my daughter I'd...
470--->'''Girl''': What would you do, Daddy?
471* Harry Chapin's "The Mayor of Candor Lied" is a particularly [[NightmareFuel bone-chilling]] twist on this one: boy meets girl, girl's father disapproves, ostensibly because the boy is poor. Boy catches his mother with her father and blackmails him into letting boy and girl be together. Then her father takes her overseas on vacation and doesn't bring her back, and in the ensuing confrontation, the boy suddenly notices how much the girl's father looks like him...
472* Music/TomLehrer wrote a jaunty, upbeat "theme song" for ''Oedipus Rex''.
473--> ''When he found what he had done, he tore his eyes out, one by one. A tragic end to a loyal son who ...'' '''''loved his mother'''''.
474* ''[[http://sniff.numachi.com/pages/tiSHMSCNDL;ttSHMSCNDL.html Shame and Scandal]]'' subverts this: This young man discovers his dad is also the father of every single one of his girlfriends [[spoiler:then learns from his mother that his "dad" his not his real father]].
475* The big reveal of Type O Negative's "Stay out of my dreams" is this trope.
476-->With your straight black hair and emerald green eyes\
477Hippies pointing "that's Pete's sister in disguise"\
478Maybe you had uttered those words as a jest\
479I don't mind the allegations of incest\
480At the time I thought I could love no other\
481Till I heard you say that I was your brother\
482In your e-mail said how much we look like twins\
483How it turned you on just knowing it's a sin
484* The song "Son Don't Go Near the Indians" -- The whole time the main character of the Western song is told "Son don't go near the Indians, please stay away." Reverse psychology plays its part, and he goes near the Indians -- a lot. He falls in love with a girl there about his age. Near the end, they resolve to get married. Only then does his father explain that his actual son got killed by the Indians, so he stole one of their baby boys, the protagonist, and that his girlfriend is his sister. "And that's why I've always said -- 'Son, don't go near the Indians, please stay away'"
485** Subverted in the related song (most likely a parody) "Son Don't Go Near the Eskimo" which leads the listener to suspect a similar conclusion, making the big reveal (the girlfriend is not his sister, but she has "the coldest nose in Alaska") somewhat anticlimactic.
486[[/folder]]
487
488[[folder:Myths & Religion]]
489* Oedipus' story in [[Myth/ClassicalMythology Greek Mythology]] involved him unknowingly marrying his own mother Jocasta. They only learned the truth years ''after'' having four kids together. Neither reacted well, Jocasta [[DrivenToSuicide killed herself]] while Oedipus [[EyeScream put out his own eyes]]. Told famously in the tragedy ''Theatre/OedipusTheKing''. Despite the way this actually plays out, Oedipus somehow ended up as the {{Trope Namer|s}} for Oedipus Complex even though he's not an example of that.
490* Averted with Telephus. He was given a beautiful woman named Auge by a king as a reward for winning a war. Suddenly, just as he gets ready, a BoltOfDivineRetribution flashes between them. Surprised, they start talking... turns out Auge is his mom, while his father is Heracles, who was apparently the one to send the lightning. Mind you, in some versions, the trope averted wasn't Surprise Incest but OffingTheOffspring - Auge still loved Heracles, so she brought a ChastityDagger along.
491* Finnish mythology: Kullervo from ''Literature/TheKalevala'' seduces a girl he meets on the road. When they find out she is his own sister who he never met, the girl commits suicide.
492* Myth/NorseMythology:
493** In ''Literature/TheSagaOfHrolfKraki'', King Helgi of Denmark marries the servant girl Yrsa whom he kidnapped on a viking raid to Saxony. It eventually turns out she is his own daughter he [[ChildByRape conceived by rape]] on an earlier raid.
494** In ''Literature/TheSagaOfTheVolsungs'', Sigmund sleeps with a vagrant soothsaying woman. Many years later, Sigmund learns the soothsayer was his sister Signy in disguise, and her son Sinfjotli who Sigmund thought was his nephew is actually (also) his son.
495* Vietnamese folk tale of Tô Thị: The titular woman accidentally married her long-lost older brother and produced a healthy son with him. When the husband found out, he left the family forever without telling them the truth. Tô Thị and her son longed for him until they both turned to stone.
496* In Russian, a few species which produce different-colored flowers on the same plant are collectively known as John-and-Mary (Иван-да-марья). The legend behind the name is that two siblings by these names were separated during a Mongol raid and made slaves. After growing up, they met, fell in love and married, but then the relationship was revealed, and they desperately prayed to God that he would allow them to remain together '''somehow'''. Hence the flowers.
497* Myth/ArthurianLegend: In the most famous version, Mordred is the result of an affair by Arthur, who grew not knowing his biological family, and his half-sister Morgause.[[note]]Though in older versions, Mordred's father was Morgause's husband Lot.[[/note]] Neither realized they were siblings, though modern versions sometimes make it so that Morgause [[AdaptationalVillainy is evil]] and [[VillainousIncest just didn't care]]. She might also be switched out with Morgan le Fay, Arthur's other half-sister.
498* In the Irish mythological text ''Literature/TheWooingOfEtain'', High King Eochaid is tricked into sleeping with his own daughter as punishment for his transgressions against the Sídhe. Overcome with shame, he orders the child of their union to be killed by being thrown to wild beasts, but she is rescued by a passing herdsman and grows up to be Mess Búachalla, mother of High King Conaire Mór.
499[[/folder]]
500
501[[folder:Oral Tradition]]
502* There's an urban legend about a married couple who keep having children with some rare deformity, like an unusual number of fingers or toes. When a doctor tells them it might be the result of inbreeding, they get nervous because one of the couple was fathered by a sperm donor. Sure enough, it turns out that said donor was the other half of the couple's dad (usually said to have given his sperm to [[StarvingStudent pay his bills]] or buy a car in college), meaning the two unknowingly had the same father.
503[[/folder]]
504
505[[folder:Podcasts]]
506* ''Podcast/RandomAssault'': The other hosts claim Drew has a lot of surprise sex with his 2 younger brothers.
507[[/folder]]
508
509[[folder:Theatre]]
510* ''Theatre/AugustOsageCounty''. [[spoiler: Little Charles and Ivy have a KissingCousins relationship, which is made worse when it's revealed that Little Charles is actually the biological son of Ivy's father, making them half-siblings as well]].
511* "[[https://en.wikipedia.org/wiki/Emmeline_(opera) Emmeline]]": In which the eponymous 19th century New England woman has an illegitimate son who is taken away from her just after birth. The son is given up for adoption and raised by a family in Ohio; Emmeline, meanwhile, saw the baby for such a short period of time, she is easily convinced by relatives that she had a daughter, not a son. Twenty years go by, and Matthew, a handsome young laborer, appears in Emmeline's hometown. They unwittingly fall in love and marry. Later, a member of Emmeline's extended family shows up to attend a funeral, and, while there, recognizes Matthew as the child Emmeline gave up long ago. After this earth-shattering reveal, Emmeline is abandoned by her son and made to be a pariah in her community, where she lives the rest of her life in miserable isolation and shame.
512* Subverted in the ''Theatre/ForbiddenBroadway'' parody of ''Theatre/SpringAwakening'':
513-->'''Mother''': Oh, God! What have you done!\
514'''Wendla and Melchior''': Mother! ''(To each other.)'' That's my mother, not yours. Stop doing that! ''(To Mother.)'' Mother!\
515'''Mother''': Actually, I am both of your mothers.\
516'''Wendla and Melchior''': Both? But that would mean... eeew!\
517'''Mother''': Let me explain. In some scenes, I am Melchior's mother, and in others, I am Wendla's. I also play a piano teacher, and when I wear this hat, I'm Frau Knuppledick. Four different characters, all wearing the same dress.
518* In ''Theatre/AFunnyThingHappenedOnTheWayToTheForum'', Philia is a virgin slave-girl arranged to be sold/married off to Miles Gloriosus, the Roman general responsible for having destroyed the land where she grew up. She is somewhat reluctant to marry even before she falls in love with Hero. But everything ends happily when a set of matching rings proves Miles and his prospective bride are long-lost siblings, enabling the hero and heroine to marry.
519* In Henrik Ibsen's ''{{Theatre/Ghosts}}'' [[spoiler: Regine turns out to be Oswald's half-sister. When the secret is finally revealed, she is not that upset about having tried to seduce her own sibling and more angry about being brought up in a lower social standing than him. Her first concern is to go get her rightful inheritance]].
520* In Carlo Gozzi's ''The Green Bird'', King Tartaglia unknowingly almost marries his own daughter Barbarina. Thankfully, the titular bird reveals the truth to them before the wedding takes place. Since Tartaglia's first wife turns out to be alive and the green bird is actually a cursed prince in love with Barbarina, no hearts stay broken.
521* Played with in ''The Guilty Mother'', the unpopular DownerEnding segment of the [[Theatre/TheBarberOfSeville Figaro]] [[Theatre/TheMarriageOfFigaro trilogy]]. Both lovers are not the biological offspring of both of their legal parents, and Figaro has to juggle their WhosYourDaddy plot so that they can marry and nobody needs to be publicly disgraced.
522* In ''Theatre/TheImportanceOfBeingEarnest'', it's revealed that Jack and Gwendolyn are long-lost cousins. In keeping with the time and place in which the play is set, this is not what destroys their relationship but rather what allows them to marry, since being Gwendolyn's cousin means that Jack is now known to be of the proper social status to marry Gwendolyn.
523* In ''Theatre/TheMarriageOfFigaro'', the character interested in marrying Figaro turns out to be his mother, and says something like she always loved him -- just in the wrong way previously.
524* It's never particularly dwelt upon (the woman in question dies minutes after announcing the fact, and everyone has more imminent problems to worry about), but towards the end of Leoš Janáček’s ''The Makropulos Affair'' it's revealed that all the time Albert Gregor has been vying for the love of his ''great-grandmother''.
525* The Roman comedy trope used in ''A Funny Thing Happened on the Way to the Forum'' was used more seriously in Gotthold Ephraim Lessing's play ''Theatre/NathanTheWise''--the title character is Jewish and it is revealed that his daughter is actually not a blood relative. He is charged with the crime of raising a Christian as a Jew. It turns out that she is the sister of a literal and celibate KnightTemplar in play (taking the place of the mercenary of Roman comedy), who other characters had been trying to fix her up with. Both of them turn out to be the children of Saladin's brother and a Christian woman, and in at least one translation, the Templar expressed gratitude at the news, as he was not yet prepared for sexual love.
526* Thomas Middleton's 1611 play ''No Wit, No Help Like a Woman's'' plays with this trope: one subplot features a young married couple who are horrified to find out they're actually brother and sister, and then quite relieved to discover that the girl was in fact switched at birth so they're not related at all.
527* The story of Oedipus who unwittingly married his own mother is the subject of Creator/{{Sophocles}}' ''Theatre/OedipusTheKing''.
528%%* Shows up in the plays of Music/SamShepard from time to time as a {{deconstruction}} of UsefulNotes/TheAmericanDream.
529[[/folder]]
530
531[[folder:Video Games]]
532* In the ''Franchise/BaldursGate'' series, Imoen and the main character (if he's male) have the sort of sorta flirty relationship you'd expect from lifelong friends of opposing genders. For that matter, if the main character's female they have the sorta flirty relationship you'd expect from lifelong friends [[QueerRomance of that sort]]. When ''Baldur's Gate II'' was released and Imoen was not one of the characters with whom you could pursue a romantic relationship, a lot of fans of the original were very surprised and rather disappointed... until [[spoiler: you found out that Imoen was your half-sister]].
533** This is actually brought up in ''VideoGame/BaldursGateIIThroneOfBhaal'' if the main character's male. Viconia insists to Imoen that given the number of times he's saved her life, she should serve him in ''every'' way. Imoen acts {{squick}}ed and cites why. Viconia brushes it off, pointing out that the common heritage would hardly one of ''blood''. Imoen then notes that -- canonically by that point -- the main character has saved ''Viconia'''s life at ''least'' twice...
534** Some people did a mod that allows this relationship; the Imoen Romance mod for ''Baldur's Gate II'' is alive and well, and is widely known for near-total freedom of choice in the protagonist's options. Imoen is romanceable by both males and females, and to the mod's credit, does not shy away from the incest issue -- Imoen in particular has issues with it.
535* In ''VideoGame/CrusaderKingsII'' it's possible for a cheating wife to pass her paramour's child off as her husband's, which the game keeps track of in an invisible character stat. It is, therefore, possible to betroth someone to their secret half-brother.
536* In ''VideoGame/{{Duskwood}}'', there's a one-sided variant between Hannah and [[spoiler:Jake, the hacker who contacts the player]]. They're half-siblings, unknown to her but known to him. Having no other family, he reached out to her a few years before the game begins, wanting to connect. The thing is, he didn't tell her they're related, with his reasoning being that he didn't want to cause strife in her family, as his existence is the result of Hannah's father cheating on her mother. He was content to just be friends with no familial connection, but Hannah, unaware of the truth, fell in love with him. When he realized, he quickly distanced himself from her and finally cut all contact.
537* In ''VideoGame/Fallout4'', you learn that all 3rd Generation [[ArtificialPerson Synths]] are created using DNA from your baby, Shaun. This turns a romance with Curie, Magnolia or [[spoiler: Paladin Danse]] towards this trope.
538* In the ''VideoGame/FateGrandOrder'' event "Murder at Kogetsukan", [[spoiler: Harriet Violet resorted to murder to prevent this. Juliet and Eva were unknowingly the result of her one-night stand with Aaron Goldie, so Juliet couldn't be allowed to marry either of Aaron's sons. She was so paranoid that the mere knowledge of the affair would result in a full-out war between the crime families that she refused to even explain the matter to said sons when they questioned her about her motives, which results in her killing them when they rather understandably don't see what the problem is and refuse to call off the engagement.]]
539* In the ''Franchise/FireEmblem'' franchise:
540** In ''VideoGame/FireEmblemGenealogyOfTheHolyWar'':
541*** Seliph and Princess Julia seem instantly attracted to each other upon meeting, but it turns out that [[spoiler:Julia is Seliph's inbred half-sister, as Seliph's mother Deirdre was brainwashed and forced to breed with her half-brother Arvis (who had no idea that they were siblings). There's a reason that the game's RelationshipValues system won't allow them to be paired--unless you exploit a programming glitch]].
542*** In the first half, Claude's most popular pairing is with Sylvia, who is hinted to be his long-lost sister, but said by WordOfGod to be a distant cousin.
543** In ''VideoGame/FireEmblemAwakening'' it was implied that Lissa was smitten with a man posing as Marth who had saved her from [[NotUsingTheZWord Risen]]. Keep in mind, that Marth is her ''distant ancestor'', [[spoiler:but it turns out that 'Marth' was actually Lissa's ''niece from the future''.]]
544** In ''VideoGame/FireEmblemFates'', [[spoiler:the Male Avatar]] gets a nice dose of ShipTease with [[spoiler:Azura]]...and then the GoldenPath reveals they're cousins. And since TheReveal doesn't occur until almost the end of the game, there's a solid chance they'll be married at that point. Given the medieval-esque setting, though, and how neither seems to particularly care about the relation if they ''are'' married, marrying one's cousin is probably seen as an acceptable thing. And note TheReveal ''only'' happens extremely late in the GoldenPath: they could theoretically marry in ''any'' of the paths, meaning in two of them they never find out they're cousins.
545* In the first ''VideoGame/KillerInstinct'' game, Black Orchid has a finishing move where she unzips the front of her outfit and flashes her breasts to her opponent, causing male characters (including Jago) to pass out in excitement. At the end of the game, she learns that Jago is her long lost brother.
546* Used in ''VideoGame/NoMoreHeroes'' when [[spoiler:Travis is informed that his ex-girlfriend Jeane, who he did sleep with, was his half-sister, which she knew beforehand. He reacts appropriately]].
547* ''VideoGame/OctopathTravelerII'' has a fairly minor yet also very spoiler-y example in Throné's story. [[spoiler:Scaracci implies that he's attracted to Throné in her first chapter and asks her to "help him out" using her hands. Throné immediately picks up on the innuendo and is annoyed by it. Fortunately, it goes nowhere, since her final chapter reveals that most (if not all) of the criminal orginization they're a part of are ''half-siblings'' with the same [[ImmortalityPromiscuity immortal]] father.]]
548* ''VideoGame/SailorMoonAnotherStory'': George and Mary, a minor couple that Sailor Jupiter helps get together in her chapter, at the end get revealed that the reason why their fathers are so angry at each other, is because George's father eloped with [[MySisterIsOffLimits the younger sister of Mary's father]], making them cousins.
549* All over the place in the 0verflow universe (which ''VisualNovel/SchoolDays'' is a part of), thanks to the omnipresent patriarch [[HandsomeLech Tomaru]] [[SerialRapist Sawagoe]] banging ''[[ReallyGetsAround a lot]]'' of women [[VillainousIncest (even]] [[ParentalIncest those]] [[BrotherSisterIncest related]] to him) and maintaining his secrecy in regards to his kinship with many characters. As a result, a lot of characters who are in romantic or sexual relationships share a familial connection that can be traced back to the TangledFamilyTree that he has made. One prominent example would be [[spoiler:Makoto]] with [[spoiler:Sekai & Setsuna]], who are AT BEST half-uncle and half-nieces thanks to the former being Tomaru's son with one of his nurses and the latter two being Tomaru's granddaughters with other relatives[[note]]For further context as to how horribly inbred their babies are, here's the rundown: [[spoiler:Tomaru and his half-sister Moegi are the parents of Kagura and Youko. Tomaru also impregnated Kagura's friend Hatsuka with a son named Shun. Shun ALSO ReallyGetsAround and has fathered several of the heroines, including Sekai who is his daughter with Youko. Setsuna is Shun's daughter with Mai. Mai happens to be one of the many children Tomaru sired by Kagura, his daughter/half-niece. And while the [[WordOfGod canonical]] family tree only confirms that Makoto gets Sekai and Setsuna pregnant, there are routes in ''VisualNovel/ShinyDays'' where Youko and Mai have his babies too]][[/note]].
550* In ''VideoGame/ShadowHeartsCovenant'', the hero Yuri meets the babealicious Karin and the two go through many harrowing adventures together. It becomes clear pretty quickly that Karin is falling for Yuri, although he's still pining over his lost love from the first game in the series. However, at the end [[spoiler: due to some messing around with the space-time continuum, Karin ends up traveling back in time and marrying Yuri's father...and becoming Yuri's mother. Good thing they never actually got together, eh]]? This makes sense in a twisted way. [[spoiler: Considering that Yuri and his father were apparently very similar people, it does make sense that Karin first falls for Yuri in her time and for his father in the past. While they only remained friends, Yuri does manage to convince Karin to wear a very skimpy outfit. The scene becomes either [[HarsherInHindsight squicky]] or more [[HilariousInHindsight hilarious]] afterwards depending on how perverted your sense of humor is]].
551* In the [=PS2=] adventure game ''VideoGame/ShadowOfDestiny'', with Eike and Dana living happily ever after, despite secretly being biologically father-and-daughter, in Ending E.
552** Well, there's a reason why it's one of the worst endings. And Dana seems to be at least subconsciously aware of the connection on some level and is bothered by it.
553* In ''VideoGame/ShinMegamiTenseiII'', for most of the story, there's plenty of ShipTease between [[HeroicMime Aleph]] and [[MsFanservice Hiroko]]. Later, it is revealed that Hiroko's missing son that she was looking for since the beginning of the story was actually Aleph all along. Aleph was a [[DesignerBabies genetically-engineered]] ArtificialHuman created by [[LawfulEvil The Center]] and Hiroko was selected to be his surrogate mother. Due to his altered biology, he [[RapidAging aged very rapidly]] to the point where he appeared to be the same age as Hiroko when they first met.
554* Shows up occasionally in works made with ''VideoGame/TheSims2'': unattended children can be taken away by a social worker, and then adopted into a different family. The adoption code deletes the family connection to the birth parents and creates one with the adoptive parent(s). Some players have used this loophole to have siblings or even twins, adopted into different families, strike up romances. Since there's no genetic penalty for incest, they can even have kids. [[http://www.moreawesomethanyou.com/smf/index.php/topic,11779.0.html Read all about it]].
555* One of the big twists in ''VideoGame/TwelveMinutes'' is that the husband and wife are really half-siblings (which the husband finds out after impregnating her). The husband suppressed the knowledge and it only came out after getting stuck in a GroundhogDayLoop.
556* ''VisualNovel/UminekoWhenTheyCry'': [[spoiler:Sayo]] discovers their true identity as [[spoiler:Kinzo's bastard ParentalIncest ChildByRape]], putting their attraction to [[spoiler:Battler, George, and Jessica]] firmly in this trope.
557* At the end of the True Pacifist route of ''VideoGame/{{Undertale}}'', the married dog couple Dogamy and Dogaressa are briefly concerned that [[spoiler: their parents having merged into an Amalgamate]] might technically make them siblings. They conclude that since they're dogs, [[SubvertedTrope they don't have an incest taboo anyway, so it doesn't matter]].
558* The CasualVideoGame ''VideoGame/VirtualVillagers'' allows you to control up to ninety individual village-members with their own names, appearance, and skills. The females can get knocked-up. By anybody. That includes their brothers, fathers, and offspring (assuming the offspring is old enough). Thankfully, the game doesn't actually keep track of family relations (which is probably why this is possible), sparing the sensibilities of players who forget or don't pay much attention to the lineage. Or turn their back on randy relations for half a second.
559* ''VisualNovel/YuminaTheEthereal'' has a NotBloodSiblings example. [[IdiotHero Yumina Midorishita]] is the biological daughter of [[MissingMom Yumika Midorishita]], while [[SupportingProtagonist Ayumu Akashima]] is the adopted son of [[DisappearedDad Takehito Akashima]]. Later on, it's revealed that Yumika and Takehito were HighSchoolSweethearts and that Takehito is also Yumina's biological father. In Yumina's route as well as the True ending, Yumina and Ayumu fall in love and hook up before the revelation that their parents are lovers, but even after they find out, they don't realize the implications that they're technically siblings until someone else points it out much later. Their immediate reaction is [[{{Squick}} embarassment and disgust]], followed by Ayumu trying to justify that it's okay because he's adopted while Yumina tells everyone (including Ayumu) to shut up because she doesn't want to think about how weird it is that her boyfriend is her brother, adopted or not. It doesn't help that Takehito fully acknowledges that they're both his children while still being [[ShipperOnDeck extremely supportive of their relationship]]. Fortunately for them, the fact that they're siblings was never mentioned again after this scene.
560[[/folder]]
561
562[[folder:Web Animation]]
563* In the ''WebAnimation/ActuallyHappened'' video ''I Saw Something CREEPY In My Bf's Old Family Album'', the twist is that the girl is dating a [[KissingCousins cousin]] she never knew about. She promptly breaks up with him, but never tells him that they're cousins.
564* In the ''WebAnimation/DorklyOriginals'' animation, "[[https://youtu.be/pgH10qoBLTM If video games were 69% more realistic]]", Diddy Kong realizes his last name is the same as Dixie's, Candy's, and Donkey Kong's, and he immediately questions if they are related, which is confirmed when all four of them say the name of their grandfather, Cranky Kong.
565--> '''Donkey Kong:''' Okay. So... Honestly, our history of incest [[ThisExplainsSoMuch explains a lot]].
566[[/folder]]
567
568[[folder:Web Comics]]
569* Creator/AGnosis' retelling of Myth/ClassicalMythology has one-sided surprise incest between Zeus and [[ParentalIncest his daughter]] Persephone. By the time Persephone realizes that Zeus pulled a BedTrick on her, [[spoiler:she's pregnant]].
570* In ''Webcomic/ArthurKingOfTimeAndSpace'', Arthur sleeps with Morgan (in the space arc) and Morguase (in the baseline arc) without realizing the relationship. (Or vice versa -- when Merlin finds out about Morgan he specifically notes that she should have been able to figure out who the mother of the rightful king must have been, but apparently she didn't. And Morguase didn't either, because if she had she'd have realized that her spell wouldn't work properly.)
571** In a {{Downplayed}} version, Gawain flirts with his [[GenderFlip sister]] Garet in the space arc, because she's disguised and he hasn't seen her in years.
572* Played for laughs in ''Webcomic/AwkwardZombie'' in one comic, where [[VideoGame/FireEmblemShadowDragonAndTheBladeOfLight Marth]] finds himself attracted to [[VideoGame/FireEmblemAwakening Lucina]]. When she reveals that she's his (very distant) descendant, Marth realizes that explained his attraction perfectly: Awkward Zombie's [[AlternativeCharacterInterpretation version]] of Marth is a narcissist.
573* In ''Webcomic/BlackAdventures'', Black has a crush on his childhood friend White and is shocked to learn from Mom that she's his twin sister, [[SolomonDivorce who went with their father after the divorce]]. Mom is oblivious to Black's romantic intent and never got around to telling him that they're related until right before he was going to confess.
574* In Chapter Twelve of ''Webcomic/{{Evon}}'', Herodotus and Evon discover (to Evon's horror) that Corrin, the magic student she had a fling with in Chapter 4, is the half-sibling of Evon's they were hoping to find. It didn't help that Corrin got over his shock at warp speed and decided that silly little things like societal taboos don't apply to them because ScrewTheRulesIHaveSupernaturalPowers.
575* ''Webcomic/FateTypeRedline'': Kanata Akagi is a boy from 2020 who gets sent to 1945 and caught up in a Holy Grail War. He meets a girl named Tsukumo Fujimiya and they blush around each other, until he realizes she is the younger version of his grandmother.
576* Happens in Webcomic/{{Hiimdaisy}}'s parody of ''VisualNovel/ApolloJusticeAceAttorney'', where it is revealed that the eponymous lawyer and his assistant and Phoenix's adoptive daughter Trucy are half-siblings from their mother's side. The game keeps mum about this and so do the two [[VisualNovel/PhoenixWrightAceAttorneyDualDestinies following]] [[VisualNovel/PhoenixWrightAceAttorneySpiritOfJustice entries]] although the latter does include [[TheStinger a stinger]] where Phoenix tells their mother that it's time for Apollo and Trucy to know the truth. Time will tell if they did address it or not. Of course, the comic follows a path where they never found out, thus leading to this trope.
577* ''Webcomic/{{Homestuck}}'':
578** Happens twice to Dave Strider. He used to hit on Rose (ironically) before learning that they were brother and sister. In Act 6, he and Rose see their [[spoiler:alternate universe]] mother in a dream, resulting in the following conversation later:
579--->'''ROSE:''' You're wondering why I didn't tell you?\
580'''DAVE:''' no\
581'''ROSE:''' You're specifically wondering why I wasn't forthcoming with an answer to your question at the time, "hey who was that choice babe in the pajamas?"\
582'''DAVE:''' god fucking dammit
583** Dave is an absolute Freudian field trip. It can be seen several times that he has an awkward attraction to the other members of his ectobiological family.
584--->'''TT:''' We've already established that all of your dreams are packed with enough homoerotic symbolism to lift Freudian theory from the ashes of discreditation.
585* In ''Webcomic/{{Shortpacked}},'' Amber learns that her AbhorrentAdmirer, the incredibly perverted Faz, is actually her half-brother due to her father's adultery. She's legitimately worried that he'll ''still'' hit on her after finding out, though, and puts off telling him until [[spoiler:their dad's death]] forces the issue. Faz does lose interest in Amber, but even then it seems to be more a combination of a.) feeling betrayed that Amber didn't tell him sooner and b.) having found an actual girlfriend (who is ''also'' super pervy and probably would've been fine with an incestuous threesome).
586* Inverted in ''Webcomic/SomethingPositive'': [[https://somethingpositive.net/comic/family-s-a-gamble-pt-9/ Vanessa slept with a guy called Brad (she was trying to figure out if she was in fact a lesbian)]] but it went no further, and later their parents were due to be married. Unfortunately, Brad choosing that moment to joke about the prior relationship caused Vanessa's mother to disown her, and later Brad's father dumped her, citing her treatment of her daughter.
587[[/folder]]
588
589[[folder:Web Videos]]
590* In ''WebVideo/ComixFromTheUnderground'', the Comix Scrutinizer reads ''Kit n Kay Boodle'' and is surprised to learn that the main characters, who constantly have sex throughout the comic, are not married, but have the same last name. Even after joking that the characters might be [[BrotherSisterIncest brother and sister]].
591* In the first campaign of ''WebVideo/CriticalRole'', [[HornyBard Scanlan]] meets an attractive gnome musician who is working with some old friends of his, and the two flirt, compete and generally hit it off. Later, the friends have come back to stay the night with Vox Machina and the two gnomes head up to Scanlan's room...where Kaylie reveals that she is Scanlan's daughter from a [[ReallyGetsAround brief relationship]] he had years ago, and she's come to kill him in revenge for leaving her pregnant mother. Scanlan is ''horrified'' and remorseful.
592* ''WebVideo/{{Gayle}}'': At least a couple times, Gayle is deluded enough (through constantly talking about Greek yogurt the first time, and heatstroke the second) that she hallucinates that her daughter Terry is Gayle's celeb crush Yanni, and starts 'getting flirty' with Terry. Terry is...unamused both times. (Made funnier by the CastIncest subtext: Creator/ChrisFleming, who plays Gayle, is dating Melissa Strype, who plays Terry.)
593-->'''Terry:''' Christ, she thinks I'm Yanni again.
594* The original plot of WebVideo/TheNostalgiaChick's "Thanks for the Feedback" would have been a parody of Luke and Leia, with she and WebVideo/TheNostalgiaCritic finding out they were related after having sex.
595* ''WebVideo/RealTimeFandub'':
596** In the ''VideoGame/SonicAdventure2'' dub, one RunningGag was Shadow the Hedgehog fucking (and pissing on to mark his ownership) Eggman's wife Martha. Then in ''VideoGame/SonicTheHedgehog2006'', [[LukeIAmYourFather Eggman calls Shadow his "greatest creation"]]. Or in other words, [[MemeticMutation Shadow the Hedgehog is a bitch-ass motherfucker.]]
597-->'''Shadow:''' Well, if you're my dad, that makes the last dub horrifying. ''God...''
598** After a brief HopeSpot when [[VideoGame/SpiderManPS4 Peter]] returns with the anti-[[ForcedTransformation table]] serum, Aunt May ultimately dies when the embarassment of finding out Spider-Man is her nephew ''right after flirting with Spidey'' drives her to will herself to death.
599-->'''May:''' Well this got weird real quick! Sorry about your whole shit! Listen. Listen! You better go, 'cause this got really weird, and I'm gonna die. I'm goin' to the fuckin' car with Creator/TobeyMaguire...\
600'''Peter:''' I know, it's so weird! I don't want you to die, Aunt May!\
601'''May:''' I'm goin' to Tobey Maguire Land, and it's the ''[[IncurableCoughOfDeath [deathly cough] ]]''
602[[/folder]]
603
604[[folder:Western Animation]]
605* ''WesternAnimation/TheAmazingWorldOfGumball'': In "The Slide", Mrs. Robinson is mentioned to have always told Rocky he had a face "only a mother could love." Seconds after being told such, Gumball realizes she unknowingly sent a date request to her own son, which Gumball rejects and covers up.
606* Used in every Creator/SethMacFarlane show.
607** ''WesternAnimation/FamilyGuy'':
608*** Happens in a Halloween episode. Meg and her friends actually get invited to a costume party, and she goes dressed as a Slutty Cat, complete with a mask covering 75% of her face. One game of spin the bottle/seven minutes of heaven later, she's escorted to the closet with someone in an all-concealing [[Franchise/{{Transformers}} Optimus Prime]] costume. When they're in there too long, the door is opened to reveal it being Chris... While they're half-naked on the ground making out. [[{{Squick}} They didn't take it well]], and lines like "We did so much!" imply there was more than just lips involved, though they seemed to have gotten over it by the end of the episode, apparently realizing that (given who they are) they were lucky to hook up with anyone at all that night.
609*** In "Valentine's Day in Quahog", Stewie decides to go back in time to the 60s to see what love was like. During the trip, he falls for a girl and kisses her, only to find out it is really Lois after she is picked up by Carl Pewterschmidt. Stewie ends up vomiting all the way back to the present.
610** ''WesternAnimation/AmericanDad''
611*** A version of this played out in an episode where Roger painted a nude portrait of Hayley for an art class, then rented it out to Steve as masturbation material[[note]]he didn't know it was her because the painting stopped at her lips[[/note]]. Hayley is naturally {{Squick}}ed and tries to put a stop to it; at the end of the episode, Roger drops the bomb, which horrifies poor Steve (rather than blaming him, Hayley is sympathetic and just gets angrier at Roger for manipulating him).
612*** In another episode Roger plays a prank where he makes Steve believe that Francine and Stan aren't his real parents. Under his false impression, he suddenly kisses a horrified Hayley, to Roger's delight.
613** On ''WesternAnimation/TheClevelandShow'', Roberta wears a fat suit using a fake name to see if she can get by without her looks, and sure enough, the only person who treats her kindly is her stepbrother, Junior. Unfortunately, he soon develops a crush on her, and she has to pretend to move away to avoid breaking his heart or revealing the truth.
614* ''WesternAnimation/CentralPark'': In Season 3 "[[Recap/CentralParkS3E07SlumberDogMollyAnAire Slumber-Dog-Molly-An-Aire]]", Shauna gets a text message from Marcus saying he'll be in Central Park with a friend from a different school and Shauna wants Molly and Hazel to come with her so she her future boyfriend. When Molly, Hazel, and Shauna finally meet Marcus and his friend, Shauna is disappointed to learn that Marcus' friend is her cousin, Bobby. Everyone is squicked out with the revelation.
615-->'''Shauna:''' ''(disappointed)'' Hey, Bobby.\
616'''Bobby:''' Oh. What's up, Shauna?\
617'''Molly:''' Wait. You guys know each other?\
618'''Shauna & Bobby:''' We're cousins.\
619'''Marcus:''' Whoa.\
620'''Molly:''' Ew.\
621'''Hazel:''' Nope. Don't do that.
622* The episode "Roswell that Ends Well" in ''WesternAnimation/{{Futurama}}''. While stuck in 1947, Fry accidentally gets his grandfather killed and figures that since he still exists, the attractive woman he thought was his grandmother couldn't possibly be. After he does "the nasty in the past-y", Professor Farnsworth explains to Fry that not only is she his grandmother after all, Fry's grandfather is [[spoiler: [[MyOwnGrampa Fry himself]]. By extension this makes Fry's parents' marriage incestuous due to the same StableTimeLoop, but neither could possibly know about that]].
623* In ''WesternAnimation/GIJoeARealAmericanHero'', Lady Jaye once infiltrated Cobra by impersonating the Baroness. At one point, she kisses Baroness' boyfriend Destro. A later episode revealed Lady Jaye and Destro share common ancestors.
624* ''WesternAnimation/TheLegendOfVoxMachina'': Scanlan, a HornyBard who flirts and sleeps with anyone who will have him, meets an abrasive gnomish woman named Kaylie during Vox Machina's attack on the Herd of Storms in Westruun. During the celebrations afterwards, Scanlan invites Kaylie up to his room, and she accepts. Once in the room, she ties him to the bed under the pretense of BDSM, [[spoiler:before putting a dagger to his throat and telling him [[LukeYouAreMyFather she's his daughter]], here to kill him for abandoning her mother after a one-night stand. Scanlan is mortified, both because he forgot Kaylie's mother even existed, and for nearly sleeping with his own daughter without knowing it.]]
625* {{Subverted|Trope}} in ''WesternAnimation/KingOfTheHill:''
626** Joseph is getting closer to a girl who is actually his half-sister (since he remains ignorant about John Redcorn being his biological father). Peggy [[InvokedTrope invokes]] FriendVersusLover with Bobby, making sure he's always hanging around them so that they can't actually do anything together.
627** Also subverted in another episode: [[ThisLoserIsYou Bill]] goes back to his family's home and meets three women who want to jump his bones. The catch is that one is his blood cousin while the others are the widows of his male cousins, and he doesn't know which is which. By the end of the episode, he figures it out and [[AllegedlyDateless manages to sleep with both of the others]].
628* ''WesternAnimation/MikeTysonMysteries''
629** One episode involves a couple who doesn't want their daughter to marry a man. As it turns out, the man is the husband's son from [[HalfHumanHybrid an affair with a pig]]. They end up marrying despite being related (and the fact the man is half-pig). Mike and his friends are grossed out by it all.
630** The episode "Your Old Man" reveals that Yung Hee's biological father is none other than Pigeon (though only Pigeon himself finds out about this), who has hit on her numerous times, and Yung herself expressed attraction to Pigeon after seeing what he looked like as a human.
631* An episode of ''WesternAnimation/TheSimpsons'' has Mayor Quimby telling his date at a wedding to say she's his niece if anyone asks. She responds "I ''am'' your niece, Uncle Joe!", and Quimby mutters "[[MyGodWhatHaveIDone Dear God, I'm an abomination!]]"
632* Played for laughs in ''WesternAnimation/TeenageMutantNinjaTurtles1987.'' Krang is shown to be watching a soap opera, featuring two characters in a passionate love affair. Marcia reluctantly explains to John that they can't marry because she's his twin sister, from whom he was SeparatedAtBirth during a hospital blackout. John assures her that it's all right because he's not her brother - when he was born, an insane nurse switched him with another baby. Krang is openly weeping.
633-->'''Krang:''' It's so *sob* true to life!
634* A technical version appears in ''WesternAnimation/TeenageMutantNinjaTurtles2012''. [[TheLeader Leonardo]] and Karai have a very DatingCatwoman relationship. It's later revealed that [[spoiler:Karai is Splinter's daughter, making her and Leo NotBloodSiblings]].
635[[/folder]]
636
637[[folder:Real Life]]
638* There was [[http://en.wikipedia.org/wiki/Cecil_Jacobson an incident in Virginia]] where a doctor (secretly) used his own sperm for all his artificial inseminations, meaning that a community now has many couples who might well be half-siblings. More of such cases of fertility fraud have been discovered over the years, including one confirmed [[https://edition.cnn.com/2024/02/14/us/fertility-fraud-accidental-incest-invs/index.html case]] where a woman discussing her own discovery of her actual paternity at her high school reunion led her former boyfriend to investigate his own donor paternity, with the revelation that they were indeed half-siblings. Another woman with several donor half-siblings chose to pursue AgeGapRomance in order to avert this possibility.
639* A Minnesota school hosts a pep assembly. Part of it is having various athletes receiving blindfolded special kisses from a secret admirer... [[http://articles.nydailynews.com/2011-12-16/news/30526908_1_pep-rally-viral-videos-prank their parents.]]
640** This is a classic pep rally "gag" of long tradition, though normally it is much more innocent. Blindfolded football players are told they must guess which cheerleader kissed them (usually just a chaste peck on the cheek)... lift blindfold -- surprise! It was actually Mom -- ha-ha. (Embarrassment and teasing ensue.) However, in the incident referenced above, parents were practically making out with their kids.
641* Happened to no less than [[http://www.spoliamag.com/the-time-casanova-almost-accidentally-married-his-daughter/ Giacomo Casanova]]. According to his autobiography, he was on the verge of marrying a beautiful seventeen-year-old girl when he recognized the girl's mother as a former lover... from seventeen years earlier. She confirmed the girl was his. In real life he broke off the engagement immediately; in his liberally fictionalized autobiography, however, he cheerfully admits to an incestuous threesome, and even [[ParentalIncest impregnated]] the daughter with their [[RefugeInAudacity son/grandson]] years later when they meet again.
642* Chevalier de Villiers entered high society under the tutelage of French philosopher and patron of the arts [[http://www.iep.utm.edu/lenclos/ Anne "Ninon" de l'Enclos]]. Ninon, a (former) courtesan and beauty, had drawn the hearts of men to her throughout her life, and the heart of the Chevalier was no exception. He proclaimed his love and passion for her, only to be sent away. After begging for the privilege of seeing her again, he violated the condition of truce and declared his love once more. Using the reason of age, Ninon claimed that it would be unbecoming of her sixty-five years (to his 20s) to love and be loved. The Chevalier wouldn't take "no" for an answer, and Ninon [[BreakHisHeartToSaveHim withdrew even her friendship]] from him. Upon discovery that the Chevalier had fallen into despair and fury on account of her rejection, she elected to see him to tell him the AwfulTruth: [[LukeIAmYourFather "The lover you are pursuing is your mother."]] Ninon burst into tears and held her son to her heart, and the Chevalier -- who could not bring himself to utter the name 'mother' to the one whom he felt such a burning passion for -- trembled, stared longingly into her eyes, and fled into the garden with a deep sigh. Ninon followed, and beneath the starry sky, the image before her was that of her son weltering in his own blood, shed by his own hand for his love for her. His dying eyes turned toward her and still shone of ardent love for her, and he passed while still uttering words of endearment.
643--> '''Ninon''': It is my son who sighs at my feet, who talks to me of love.
644* There was a [[http://www.guardian.co.uk/uk/2008/jan/11/allegrastratton case in the UK]] where twins who were separated at birth got married without realizing they were related. They had the marriage annulled after they discovered the truth.
645* Somewhere in Britain there allegedly is a gravestone raised in the late 17th century to a woman who was the buyer's "mother, sister, mistress and wife". Apparently the deceased was impregnated as a young woman by her own father; the baby boy was sent to another village and came back a man, started an affair with an older woman he met there and later married her, and only then did she recognise a birthmark on his body...
646%%* [[http://www.reddit.com/r/AskReddit/comments/23tp3i/what_is_the_most_awkward_accidental_physical/ch0qxvz This unfortunate anecdote]] from {{Website/Reddit}}.
647* In 2013, Icelandic biotechnology company [=deCODE genetics=] held a competition among Icelandic students to develop mobile apps which utilize the data collected in "Ìslendingabók", a genealogical database built and maintained by [=deCODE=]. The winning entry was [=ÍslendingaApp=], which, alongside various other services, allows two Icelanders who both have the app to instantly check whether, respectively in what way, they are related. The app can also be customized to give a warning called the "incest spoiler" if the two users share at least one grandparent. Though this optional feature was used to advertize [=ÍslendingaApp=] as a safeguard against accidental incest, incest prevention was never the app's primary purpose, and the "incest warning" was, at least partially, included for joke's sake. Contrary to what has been reported internationally, accidental incest is not a bigger problem in Iceland than anywhere else in the world.
648* One of the concerns with donor children not knowing who their parents are, is the potential for this issue. It’s actually more likely to happen than people realize, possibly related to the known phenomenon of people marrying those who smell like their biological parents.
649[[/folder]]

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