->''"We were raised side by side, but he was actually adopted so technically it's OK that I'm also attracted to him."''
-->-- '''Twilight Sparkle''' (talking about her brother Francis), ''WebVideo/FriendshipIsWitchcraft''
%% One quote is sufficient. Please add additional entries to the quotes tab. If you think you know a better one, post at a quote-picking forum.

A common [[WriterCopOut cop-out]] in anime, manga and {{soap opera}}s, when a series is based on BrotherSisterIncest, is to [[TheReveal reveal]] towards the end, or explicitly state in the opening monologue, that they're Not Blood Siblings. Usually, for all intents and purposes, everyone acts like they are. Alternatively, it can be used to explain why everyone's okay with the relationship.

This can also be foreshadowing for such a relationship, as many shows usually won't make a big deal about adopted children unless there's a ChangelingFantasy involved.

Sometimes this is a result of {{Bowdleri|se}}zation, {{Media Watchdog}}s, and ExecutiveMeddling, in that in the original series they were blood relations. It also comes up in {{Moe}}, for fans who, while probably not having siblings, still feel a bit too {{squick}}y about it. FirstGirlWins can sometimes explain the prevalence of this trope.

This trope is often related (but [[AccidentalPun not by blood]], of course) to FlirtyStepsiblings and LittleSisterHeroine.

As for reality, it depends. These tropes tend to gross out anyone who has been raised alongside their stepsiblings. If they met as teens or later, though, it can seem unfair that their parents got got together before they did.

In older works, when sex shouldn't even be hinted in family friendly stories, main child characters are usually [[ConvenientlyAnOrphan conveniently adopted orphans.]] That way, the main male and female character don't have to be accounted as their actual parents. This situation does lead to a lot of confusion with readers. A boy and a girl are adopted by a family, therefore appear to be brother and sister, but still have a romance thing going on and jealousy when one of them has success with another love interest. Since the situation isn't always explained, this often leads to disturbing, confusing ideas with the readers.

Quite often it's just a case of cultural misunderstanding. In Japanese the words for "big brother" (兄さん - ''nii-san'') and "big sister" (姉さん - ''nee-san'') are very commonly used in casual speech to address young people in general, too, and it's not rare that little kids and teenagers will use them to address to older but still young friends (or love interests). However, sometimes clarification is needed if the context is not clear enough about it.

----
!!Examples:

[[foldercontrol]]

[[folder:Anime & Manga]]
* Eren and Mikasa in ''Manga/AttackOnTitan'', though they're known to be adoptive siblings from the start. While Eren doesn't seem to have any romantic feelings towards Mikasa, Mikasa loves Eren to the point that she's willing to die for him, and EveryoneCanSeeIt.
* Pristine example in ''Manga/{{Miyuki}}'': The main character soon discovers that his stepsister Miyuki is not blood-related to him. She ignores it until the end of the manga [[spoiler:when he proposes in the middle of her wedding to one of his best friends. She then breaks up the wedding, and they eventually get married.]]
* In ''Manga/MarmaladeBoy'', Miki and Yuu's respective parents swap marriage partners, thus making their children step siblings. The kids fall in love with each other, and though they worry what their parents will think they don't see it as an insurmountable problem. [[spoiler:Drama ensues when Yuu discovers some circumstantial evidence suggesting that they ''are'' blood siblings, and quickly breaks up with Miki, gets the hell out of town, and leaves them both to suffer. They finally conclude that they still love each other and want to get married, but their parents reveal that it was just a misunderstanding and they're not blood siblings after all, making it a DoubleSubversion.]]
* ''Manga/LoveHina'' introduced the [[RetCon hitherto unmentioned]] Kanako, Keitaro's quasi-adopted sister. Ironically Keitaro is the ''only'' character who never rationalizes Kanako as being 'fair game', while Naru ends up taking his role of clumsy awkward relationship handler for a period of time because she does.
* Tetsuya and Jun from ''Anime/GreatMazinger'' were two orphans taken in by [[TheProfessor Kenzo Kabuto]] and were raised together. Technically they are adoptive siblings, but they are not related by blood at all, so no one bats one eyelash regarding their ongoing BelligerentSexualTension.
* In ''Manga/HotGimmick'', Hatsumi is unaware for a large portion of the series that her brother Shinogu is adopted. Shinogu, however, ''is'' aware and even moves out of their family's apartment as part of a plan to make Hatsumi see him as more than a brother. His compassionate nature also arguably makes him a [[FanPreferredCouple preferable]] match for Hatsumi, compared to her {{Jerkass}} boyfriend Ryoki.
** The novel [[spoiler: has a Shinogu/Hatsumi ending]], for those of us who thought the manga's ending was TEH FAIL.
* ''VideoGame/YoakeMaeYoriRuriiroNa'' has two sisters for the lead, neither of whom is his blood sister, and both of whom are [[TheUnwantedHarem haremettes]] in the game. (For the record, Sayaka is his cousin, and Mai was adopted).
* Likewise, in the anime ''Manga/HappyLesson'', Chitose's sisters aren't really related to him and are clearly invoking a BigSisterInstinct and CoolBigSis, but this isn't milked for {{UST}} at all.
* ''[=KissXsis=]'' runs on this trope. Keita's twin stepsisters compete with each other for his affections, much to his dismay. His parents not only are aware of this, but [[ShipperOnDeck actively encourage him to go for one of the girls]], constantly reminding him that "it's not by blood, so it's OK!"
* Kyouya in ''VisualNovel/TriangleHeart3SweetSongsForever'' has Miyuki (actually his cousin, which permits her into the UnwantedHarem), as well as Nanoha. [[Franchise/LyricalNanoha Nanoha's own series]], which barely shows Kyouya instead of giving him a lead role, doesn't even mention this, and instead chooses to briefly tease a potential relationship between Fate and her brother (by virtue of his mother adopting her) Chrono. Although this too was [[ShipSinking abandoned]] in the third season when Chrono married his [[VictoriousChildhoodFriend childhood friend, Amy]]. And Fate becomes the [[HasTwoMommies second mother]] to Nanoha's adopted daughter Vivio, anyway.
* In ''Anime/MagicalGirlLyricalNanohaStrikers'' the [[ShipTease hinted-at]] ToyShip of Erio and Caro may sort of fit this in that Fate ends up being the legal guardian of both. The accompanying ''[=StrikerS=]'' manga has them repeatedly state that they are technically adopted siblings... while lathering on even more ShipTease. Unlike other [[NotBloodSiblings non-blood siblings]], they had never met prior to ''[=StrikerS=]'', and had no pre-existing sibling relationships (they even begin on a LastNameBasis).
* [[spoiler:Hiro and Karada]] in ''Manga/AsatteNoHoukou''; not taken to a romantic end, but still important to the plot. It's implied in the manga and left unmentioned in the anime is that, [[spoiler:while not siblings, they ARE blood-related, but Karada never knows (she would be the daughter of Hiro and his aunt concived just before he went to study at the US).]]
* Has the heck spoofed out of it in ''Manga/NininGaShinobuden'' (a.k.a. ''Ninja Nonsense''), where one of the main characters, a yellow Pac-Man-esque anthropomorphic football who is really a Ninja Elder refers to this particular trope and, being a pervert, has a particular high esteem. "If the Master says there is a cute little non-blood related sister, there IS a non-blood related sister."
* Inverted in ''Anime/RevolutionaryGirlUtena'': when Nanami thinks that she and Touga ''aren't'' blood siblings, her world collapses. Turns out [[spoiler:Touga is her brother. They were both adopted.]]
* Pointed out in the visual novel-based OVA ''_summer'', where Osamu, the typical idiot best friend character, points out "Sana's technically your stepsister, so you could go for her if you want..." when looking over the many girls the protagonist has gathered around him.
* Kai and Saya from ''Anime/BloodPlus'', where it is pretty obvious from early on in the series that Kai would [[MemeticMutation hit that like the fist of an angry god]]. Nobody seems to find this at all strange. When one considers that she was only "adopted" a couple years ago (ie after Kai had hit puberty) and looked like a teen girl already, it's not so strange.
* ''Anime/CodeGeass'' played with this in one of its many [[AllThereInTheManual Sound Episodes]]. Shirley goes through a series of [[ImagineSpot Imagine Spots]] in which her attempts to ask Lelouch out go spectacularly wrong. In one of the imaginary sequences, his IllGirl little sister Nunnally enters the scene and says that they'll be late for the wedding; as Shirley recoils in shock, the pair claim that they're NotBloodSiblings, so it's okay. In reality Nunnally and Lelouch are blood related, though they still have IncestSubtext nevertheless.
* Played with in Chapter 104 in the ''Manga/ToLoveRu'' manga with Rito's younger sister, Mikan,[[http://www.mangareader.net/140-8850-14/to-love-ru/chapter-104.html "revealing" to Rito]] [[http://www.mangareader.net/140-8850-15/to-love-ru/chapter-104.html that she's not related to him by blood]] in an unexpected moment of sweetness. Of course, she was just doing it to [[http://www.mangareader.net/140-8850-16/to-love-ru/chapter-104.html mess with her older brother]]... or [[http://www.mangareader.net/140-8887-13/to-love-ru/chapter-141.html was she?]]
** And then revisited with a megaton-sized blast of ShipTease in the entirety of [[http://www.mangareader.net/140-18359-1/to-love-ru/chapter-157.html chapter 157]].
* In the manga ''{{Ani-Com}}'' by Yuu Yabuuchi (writer of ''NaishoNoTsubomi'' and other {{shojo}} manga), this is the basis of the plot. It's played out that the remarrying parents ''expected'' their two children to get together and get married, and they do.
* ''Completely'' inverted in ''Manga/KoiKaze,'' where Koshiro and Nanoka develop an attraction for each other and then find out they ''are'' blood siblings who haven't seen each other in 10 years. The story revolves around how they cope--or not--with the fact that they can't get over their feelings for each other. In fact, ''Koi Kaze'' uses the [[http://en.wikipedia.org/wiki/Genetic_sexual_attraction documented phenomenon]] of "genetic sexual attraction" as a factor in Koshiro and Nanoka's interactions.
* ''VisualNovel/AkaneiroNiSomaruSaka'' hints at this with some PlotBasedVoiceCancellation, adding a considerable cop out factor to an already frustrating ending.
* Interesting variation in the manga ''Manga/BokuNoFutatsuNoTsubasa'' when Hiromi gratuitously reminds [[{{Hermaphrodite}} Makoto]] (after a lot of borderline incestuous behavior) that they aren't blood ''cousins'', it foreshadows the reveal that Hiromi's adoptive mother is Makoto's biological mother, meaning they aren't blood sisters, either.
* In the Okazaki Tsuguo manga ''{{Justy}},'' the titular character has ''two'' of this sort of sisters (the older one "adopted" him when she found him as a lone child, and then he "adopts" the younger after he kills her criminal [=ESPer=] father), and they both have crushes on him. [[spoiler:Justy ends up romantically involved with the older one, Jerna. And he continues calling her "neesan," even when they're nude and postcoital in bed together.]]
* Subverted in ''Manga/OniichanNoKotoNankaZenzenSukiJaNaiNDakaraNe''. Shuusuke is determined to treat Nao like a sister and nothing else, [[ChivalrousPervert despite him totally having the hots for her.]] Nao, on the other hand, is actually slightly ''disappointed'' to find out that they're NotBloodSiblings, [[CovertPervert because it makes their attraction to each other less taboo.]][[note]]she quickly gets over this when it occurs to her that this means she can openly date and marry him.[[/note]]
* None of the Elmore kids in ''Manga/{{Psyren}}'' are blood-related. Probably why Fredrica and Marie is one of the most common pairings.
* ''Manga/CherryJuice'' features a boy and girl of the same age becoming step siblings as young children, who eventually grow to have the hots for each other as teenagers. Their relationship is supported by both the girl's friends and her grandmother, who does everything she can to get the two together.
* The manga, ''Manga/MeAndMyBrothers'', takes great pains to remind the reader nearly ''every chapter'' that the heroine is in fact ''not blood-related'' to the titular brothers, despite the also-incessant reminders that they are all family and that Sakura is their "little sister." This is used quite blatantly so Sakura can be obsessively fawned over by her new guardians--and eventually fall in love with one of them--without the squick.
* In ''Anime/RODTheTV'' Michelle, Maggie, and Anita are "sisters in law" rather than actual sisters, though this is more for plot reasons than pairing them together.
* The main plot of ''Manga/AkumaDeSourou''; Takeru and Kayano's parents are engaged when they begin their relationship, so understandably [[strike:they]] Kayano goes to great lengths to keep it secret. Some people in universe accept it, and others ''don't''.
* Never stated outright in ''Webcomic/AxisPowersHetalia'', but the amount of ShipTease between characters that aren't technically related by blood is astounding, as adoptive older brother figures tend to later become possible {{Love Interest}}s (in fans' eyes, at least). Possible couples include: Switzerland and Liechtenstein, China and any of the Asians, any arrangement of England/France and America/Canada, possibly Spain and Romano... And because this universe is rather unclear about how exactly countries are "born," fans can and do decide whether or not certain couples are incest based on their preferences.
** Averted with [[spoiler:Norway and Iceland]]--the latter's "DNA testing results" (archaeological excavation) prove that they are, in fact, related.
* Manga scenarist Shirodaira Kyou apparently loves playing with this.
** Played straight so far in ''Manga/ZetsuenNoTempest'' with Mahiro's dead sister.
** A variation in ''Manga/TheRecordOfAFallenVampire'': Akabara's adopted daughter fell in love with him, though he still sees her as his little girl. As a bonus, Akabara later married [[spoiler: her half-sister.]]
** In ''Manga/{{Spiral}}'', Ayumu is strongly hinted in the anime and confirmed in the manga to be in love with his sister-in-law. Inverted with [[BelligerentSexualTension Kousuke and Ryouko]], who have blatant ShipTease much before we learn (in the manga only) that they're actually half-siblings--but ''they'''ve always known it, and though they've been raised apart, it has always been an obstacle to their relationship. (They eventually do make it to OfficialCouple status.)
* Kurei and Kurenai from ''Manga/FlameOfRecca''. Mori Kouran was already the adopted father of Kurei, then he was revealed to also have adopted Kurenai when she was [[spoiler: about to be killed]]. Let's not forget that both Kurei and Kurenai were in love each each other and actually a couple in canon.
* ''Manga/SixHalf'': Akio and Shiori turn out to not actually be related, being from their father's and mother's previous marriage, respectively. Maho is their half-sister. And Akio reveals that Shiori knew this prior to the accident, but her amnesiac self most likely doesn't remember; though he doesn't know that the amnesiac Shiori has fallen in love with him.
* ''Anime/MawaruPenguindrum'' has ''two'' instances of these:
** In episode 19, it is been revealed that [[spoiler:Himari is not Kanba and Shouma's blood sister; she is actually a girl rescued from the child broiler and was adopted into Kanba and Shouma's family, and she is in love with Shouma.]]
** In the next episode, this is also revealed [[spoiler:Kanba is not really Shouma's blood brother as well.]]
** Then provides a surprise aversion: [[spoiler: Kanba and Masako are HalfIdenticalTwins. Guess Masako is into [[{{Twincest}} half-twincest]]?]]
* ''Manga/VampireGame'' has [[spoiler: Laphiji and Seilez]], although, as Ishtar has said, the family's so inbred everyone's practically married to their siblings anyways.
* At one point in ''[[http://en.wikipedia.org/wiki/Fire_Tripper Fire Tripper]]'', Suzuko falsely believes that [[spoiler: she and Shukumaru]] are brother and sister by blood. When she discovers that the two of them actually aren't blood-related, she [[spoiler: happily returns his affections and marries him]].
* In ''Manga/FamilyCompo'' Masahiko has feelings for Shion, who acts as his sister and is referred to as so. But while Shion isn't his sister, she is his [[KissingCousins cousin]].
* In the OVA adaptation of the bishoujo game ''Ko-ko-ro...'', Souji is shown in flashback to be adopted by the Kuonji family. This is apparently not lost on his younger sister, Asuka; though she addresses Souji as "Aniki" (Japanese for "older brother"), she regularly initiates intercourse with him and secretly watches him having sex with other girls in his bedroom.
** When in public, Asuka is openly affectionate and quite clingy with Souji, acting much more like his girlfriend than his sister, and seems to relish the shocked stares of people who see them together.
** The OVA scenario is about as shocking as in the revised version of the game, in which Souji and Asuka were merely stepsiblings, but neither is as shocking as that of the original release of the game, where they actually ''were'' [[BrotherSisterIncest blood siblings who had sex with each other]] and were also [[{{Squick}} sexually abused by their parents]].
* Jeremy and Ian of ''Manga/ACruelGodReigns'' fall into this category. While not blood brothers, they are brothers through adoption.
* PlayedForLaughs in ''Manga/ServantXService''. When Taishi mentioned he actually has a girlfriend, Hasebe immediately suspected this between he and his {{Tsundere}} [[BigBrotherWorship Brocon]] sister Touko. It is in fact averted, of course, as his girlfriend is [[spoiler:[[CosplayOtakuGirl Chihaya]].]]
* In ''LightNovel/ACertainMagicalIndex'', Motoharu is in love with his adopted sister Maika. She's the only person he truly cares for.
* In ''LightNovel/DateALive'', Kotori has a crush on her older foster brother Shido. He only sees her as a sister, which ticks her off. He is willing to kiss her, but only because it is the way to seal her out of control powers.
* In ''Manga/SaikinImoutoNoYousuGaChottoOkashiindaGa'', the ghost Hiyori Kotobuki often possesses Mitsuki Kanzaki and uses her body to hit on Mitsuki's stepbrother Yuya. Mitsuki finds this disgusting and humiliating, constantly managing to force Hiyori out of her body. However, as time goes on, she starts fantasizing about and blushing around Yuya even when Hiyori is not there, and getting jealous of any girls that get close to him. Yuya is confused about the whole thing, thinking Mitsuki has a split personality.
* In ''Six Half'', main character Shiori is worried over developing feelings for her brother Akio, whom she doesn't fully see as a brother due to developing amnesia from a motorcycle accident. As Akio reveals to his girlfriend, Shiori isn't related to him at all and, according to Akio, she ''knew'' this before the accident, too.
* ''Manga/SensualPhrase'' has Atsuro in a relationship with his sister Yuka. Their exposed relationship even causes a scandal, but Atsuro casually reveals to the press that they are stepsiblings.
* Played straight in ''Onii-chan Dakedo Ai Sae Areba Kankeinai yo ne!''. Akito and Akiko are apparent twins, and the entire show chronicles Akiko's efforts to get in the pants of her older brother. Only in the last episode is it revealed that Akiko's been, for the sake of his sister, [[spoiler:keeping his adoption a secret all along]].
* A disturbing example in ''Anime/KillLaKill'', where a brainwashed [[spoiler:Ryuko]] has a threesome with [[ParentalIncest her mother Ragyo]] and her stepsister Nui Harime. [[spoiler:Ryuko]] then gives Nui a goodbye kiss later. Of course, [[spoiler:Ryuko]] is not pleased when she is freed from the brainwashing.
* In ''LightNovel/SeikenTsukaiNoWorldBreak'', though Ranjou and Moroha were blood-related in a past life, in their current lives they aren't. However, Ranjou plays the trope up as if they were blood siblings, and [[ClingyJealousGirl flies into a rage]] when Shizuno gets a little too friendly with Moroha.
* In ''Anime/SwordArtOnline'', Suguha has had a strong but secret crush on her older brother Kazuto (better known by his screen name Kirito). It's mentioned that Suguha's parents are actually Kazuto's aunt and uncle, who adopted him into their family when his parents died in an accident, meaning that he and Suguha are actually [[KissingCousins first cousins]] rather than true blood siblings.
* ''Manga/{{Citrus}}'' revolves around two stepsisters who fall in love. A good deal of the conflict is due to them trying to be familial but also being attracted to each other.
* It's eventually revealed in ''Manga/{{Yuureitou}}'' that [[spoiler:Satoko]] and her AbusiveParent [[spoiler:Marube]] are most likely not blood related. [[spoiler:Marube]] had been [[VillainousIncest molesting her]] and when [[spoiler:Satoko]] learned the truth of their bond she became furious and [[TheRunaway ran away]]. Marube apparently has no qualms with blood incest either as he later [[spoiler:tries to have sex with his biological son, Tetsuo]].
* In ''Manga/FateKaleidLinerPrismaIllya'', Illya has a crush on her adopted brother Shirou, even at one point kissing him in a dream. Shirou is completely oblivious to any girl's feelings, including hers.
* Amazingly subverted in most Shounen-Ai and Yaoi mangas. Apparently, the mixture of same-sex relationships with blood relation is making a character in these works way more interesting/attractive, if going by the sheer numbers. And that isn't even counting all the [[UpToEleven twin-cest stories]].
* Silver and Blue from ''Manga/PokemonAdventures'' were both kidnapped at a young age and were raised as siblings. The manga has implications that Silver might have a crush on Blue.
* ''Manga/BunnyDrop'':
** Defied, as one of the reasons why Yukari and Daikichi don't end up together is to avoid this trope. Daikichi's adopted daughter and Yukari's son have romantic feelings for each other post-{{timeskip}} thus it would create [[FlirtyStepsiblings trouble]] if Yukari and Daikichi were ever married.
** Near the end of the manga the characters learn that [[spoiler:Rin is not the biological daughter of Daikichi's grandfather after all]]. This causes [[spoiler:Rin]] and [[spoiler:Daikichi]] to become the OfficialCouple [[spoiler:despite their over [[MayDecemberRomance twenty-four year age gap]] and [[WifeHusbandry Daikichi raising Rin]].]]
[[/folder]]

[[folder:Comic Books]]
* In the German comic ''Wendy'', does [[TheProtagonist Wendy]] date her foster-[[KissingCousins cousin]] for most of the story until her aunt decide that she didn't want to adopt him and his twin sister after all, as they aren't as rich anymore. After that he breaks up with Wendy to date his previous foster sister Vanessa instead, while implied to still live in her house. It's [[UnderStatement weird]].
* In ''ComicBook/ElfQuest'', it is hinted at in the comic, and expressly stated by the WordOfGod, that Cutter and Skywise have had sexual relationships. It is also mentioned in the comic that they are "brothers in all but blood." Of course, the elves are said to not have the same concept of relationship as (modern Western) humans do, even though nearly all of them are paired in "life bonds" (i.e. marriages).
* Mister Immortal from the ComicBook/GreatLakesAvengers learned he was immortal after his stepsister's death, which became {{Narm}}tastic after his repeated botched suicides.
* In ''Comicbook/XMen'' comics, ComicBook/{{Nightcrawler}}'s "true love" is his adoptive sister Amanda Sefton, even though they were raised together since infancy. They actually did officially get together, late in ''Comicbook/{{Excalibur}}'s'' original run (and was portrayed as a bad idea--not because of their prior relationship, but because Amanda was portrayed as not-quite-right in the head). Nightcrawler (as Mystique's blood son) and Rogue (as her adopted daughter) have potential for this, as well. Which if it happened would be less potentially squicky than Amanda; they never even met until adulthood. He still flirts shamelessly with her.
* Back in early 1980s, DCU stories set on Earth-Two hinted at mutual attraction between the Huntress (Helena Wayne, Earth-Two Batman's daughter) and the local version of Dick Grayson. It pretty much remained subtext, with both parties insisting all too earnestly that even though they weren't biologically related, their relationship would be too wrong to even contemplate. That subtext inexplicably became text in the recent ''Justice Society of America Annual''. The 1980s version was from the original [[TheMultiverse Earth Two]]. After ''ComicBook/CrisisOnInfiniteEarths'', that Universe ended. The whole point of the recent Annual was to show that the Earth-2 ComicBook/PowerGirl was sucked into was NOT the same Earth 2 she came from. And since DC destroyed and remade its universe AGAIN since then, it's all out the window anyway.
* It is heavily implied that Despair II has an unrequited crush on her adoptive brother Destruction in volume 7 of ''ComicBook/TheSandman''.
* This is a mantra for Thor/Loki or Balder/Loki fans, especially when Loki [[GenderBender was in a female body]].
* Happens not once but ''twice'' in ''ComicBook/TheUmbrellaAcademy''; first between the Rumor and Spaceboy, and then the Kracken's obvious unrequited feelings for Vanya, as well.
* In an early ''ComicBook/AlphaFlight'' story, it's strongly implied that Marrina's adopted brother was in love with her.
* ComicBook/SuskeEnWiske: Suske and Wiske are both adopted by their aunt, Tante Sidonia, and thus raised as brother and sister. Still, many readers have had the impression that they actually WERE siblings. This caused a lot of disturbing scenes where Wiske is jealous of Suske's success with other girls and a case of BrotherSisterIncest appeared to be going on.
* ''ComicStrip/{{Nero}}'': Petoetje and Petatje are also adopted and raised as brother and sister by Madam Pheip.
* In ''ComicBook/PrinceOfPersiaTheGraphicNovel'', Layth and Guilan are married before the story begins. They were raised as brother and sister after Saman, Guilan's father, defeated the Caliph's army and killed Layth's real father in battle.
* In ''Comicbook/TheKingdomDC,'' Nightstar, the daughter of ComicBook/{{Nightwing}} and [[GreenSkinnedSpaceBabe Starfire]], hooks up with Ibn al Xu'ffasch, the son of Franchise/{{Batman}} and [[MadScientistsBeautifulDaughter Talia al-Ghul]]. Batman raised Nightwing and even legally adopted him in the main DC universe, making these two kinda-sorta uncle and niece. This is one reason Dick is not especially happy with their relationship.
[[/folder]]

[[folder:Fan Works]]
* ''WesternAnimation/PhineasAndFerb'' often fall into this; they're canonically stepbrothers, but ''refer'' to each other as brothers and have been raised together since they were toddlers. Slightly less commonly they'll be paired with their older sister (biological for Phineas, step- for Ferb) Candace.
* ''Series/DrakeAndJosh'' has a few examples between the titular stepbrothers.
* Dib and Gaz from ''WesternAnimation/InvaderZim'' are brother and sister, but WordOfGod hints that Dib may have been an experiment created by their scientist father (and, many fans guess, Gaz too). Some have argued this makes them a viable shipping pair. It's not a very popular ship, though.
* Derek and Casey of ''LifeWithDerek'' is a non-canon ship that's largely popular with the fanbase, as opposed to all the other love interests that are introduced throughout the series. The fact that half of the show focuses on the interactions and the relationship between the two stepsiblings doesn't help.
** As a sort of [[BetaCouple Beta]] FanPreferredCouple of sorts, there's also Edwin and Lizzie, the younger siblings of Derek and Casey respectively. Doesn't help that both sometimes use the closet as a meeting place, which immediately has shippers thinking of the TenMinutesInTheCloset trope.
* Many ''Literature/ChroniclesOfNarnia'' fans use this excuse in [[BrotherSisterIncest Edmund/Lucy and Peter/Susan]] stories.
* The ''Literature/{{Twilight}}'' fanfiction, ''[[https://www.fanfiction.net/s/5176801/1/Dark-Whispers Dark Whispers]]'' features Bella and Jasper as the main characters. They are brother and sister, their father is abusive and Jasper ends up killing him, before he runs aways with Bella. The main focus of the story is how an [[{{Yandere}} almost obsessive]] Jasper engages in all kinds of sexual activities with his little sister, before they find out at the end that [[spoiler: they're not actually related]].
* Even though ''Toys/{{Bionicle}}'' is supposed to be a NoHuggingNoKissing universe, (any romantic subtexts in the movies are [[CanonDisContinuity discontinuities]]) there's a good deal of romance in FanFiction. A lot of it is between members of the same team who call each other "brother" and "sister". Not as [[{{Squick}} squicky]] when you realize that the entire cast is made of [[WhatMeasureIsANonHuman mostly machine cyborgs]] and that "brother" is more a title of endearment than anything.
* In the GenderFlip-based ''[[WesternAnimation/{{Daria}} John Lane]]'' fanfic series, this happens in a more justified situation--after Helen learns how totally neglectful John's parents are, she takes them to court and takes custody of John Lane, who at that point is already in a budding relationship with Daria.
* Mari tries to use this argument with [[OriginalCharacter Uri]] in ''Fanfic/NobodyDies''; he shoots her down regardless, still {{squick}}ed by the prospect.
* In one ''Manga/{{Naruto}}'' fan comic, Temari discovers her father's secret papers, which prove that she was actually adopted, and doesn't have to hide her feelings for her younger brother Gaara any longer. Kankuro then wonders if he can do the same for Gaara, but Temari beats him up while reminding him that he and Gaara are still related, since ''she's'' the one who was adopted.
* ''Fanfic/OneiroiSeries'': Terentius briefly tries to use this rationale to excuse himself from [[ADateWithRosiePalms wanting]] [[BrotherSisterIncest his adopted half-sister]], but he quickly breaks down, admitting to himself that it really doesn't matter and that he was lusting after his little sister.
* Subverted in Fanfic/RelationshipsSeries. When it comes to light that Nove and Ginga, who are in a three-way relationship with each other and Wendi, are genetically related, this revelation [[spoiler:motivates Genya's decision to send Ginga on a mission to separate her from Nove and Wendi]].
* In ''FanFic/LegolasByLaura'', the eponymous elf adopts the heroine [[MarySue Laura]] as either his sister or his daughter (it's not really made clear). After rescuing her from orcs, he agrees to "be your boyfriend," even though she's both his adopted sister and [[{{Lolicon}} ten years old]].
* The ''Franchise/StarWars'' fanfic "Father and Son" has Han and Leia as a couple (as in canon) despite the fact that her (and Luke's) birth parents adopted and raised Han for several years before the twins were born. Somehow, nobody (not even Vader or Padme's extended family on Naboo) sees anything wrong with the two being a couple. (Admittedly, all three siblings were sent to separate planets after Anakin's FaceHeelTurn and Padme's DeathByChildbirth, and didn't find out about their being siblings until after they were all adults. But still.)
* Most fanfiction for the pairing of Shadow the Hedgehog and Maria Robotnik from ''Franchise/SonicTheHedgehog'' downplay the LikeBrotherAndSister aspect their relationship may or may not have had.
* Thor and Loki of the Marvel universe tend to be the subject of some arguments regarding whether or not pairing them constitutes incest. On the one hand, they were raised together and usually refer to each other as brothers (albeit somewhat sarcastically), but being that Loki is an adopted frost giant and goes by Laufeyson and not Odinson, whether or not they both see each other as siblings depends on the writer.
* A few ''WesternAnimation/YinYangYo'' fans use this to justify the {{Twincest}}.
* A source of some discomfort to Shinji in ''Fanfic/DoingItRightThisTime''. First he had what he thought was a near-miss with SurpriseIncest before the whole PeggySue thing happened, but now it turns out Rei wasn't a clone of who everyone thought she was and they're definitely not even siblings by adoption ([[YouAreNotMyFather Rei's pretty emphatic about that]]) and he has no idea if that makes the time he accidentally saw her naked better or worse. Especially because [[LoveTriangle he has a bit of a thing for Asuka as well.]]
* As the quote above demonstrates, ''WebVideo/FriendshipIsWitchcraft'''s [[WesternAnimation/MyLittlePonyFriendshipIsMagic Twilight Sparkle]] justifies having a crush on her brother Francis (that universe's version of Shining Armor) by pointing out that Francis was a DoorstopBaby left at Twilight's house. Even after her explanation, the other ponies still find the attraction creepy. [[spoiler:Twilight [[MurderTheHypotenuse wins in the end]], and eventually marries Francis.]]
* Invoked in the ''Disney/{{Frozen}}'' fanfic ''[[http://archiveofourown.org/works/1086925 We Can't Be Wrong Tonight]]''. Elsa and Anna order fake documents created that show that Anna was adopted. The two are biologically sisters, however they want to be open of their relationship and marry each other. Anna has a resemblance to her father but looks different enough from the rest of the family for it to work.
[[/folder]]

[[folder:Films -- Animation]]
* ''Disney/TheLionKing'':
** There are constant debates on who, if Scar and Mufasa are the lions of the pPride, Nala's father might be, and thus to what extent she is related to Simba. A full-on sibling seems unlikely, but she could easily be the daughter of Mufasa and another lioness; barring this, she may be the daughter of Scar, which is uncomfortable for ''several other reasons'': in some drafts (and in the Broadway musical), Scar actually tries to make Nala his consort, which is the real reason she exiled herself from the Pride. You see [[PervertDad what the problem with that is]]. Moreover, in the sequel, Nala and Simba's daughter Kiara hooks up with Scar's adopted son (well… supposedly, see the third bullet-point here), which is just as weird.[[note]]According to ''WesternAnimation/TheLionGuard'', Nala's father is an unknown male [[DisappearedDad who died or disappeared in unknown circumstances prior to the events of the films]]. Some fans have been reluctant to accept this explanation (as well as other [[RetCon retcons]] done by the series) and declare it FanonDiscontinuity altogether.]]
** There's also debate on whether Shenzi, Banzai, and Ed are related, partly for the purpose of writing fanfiction with the Shenzi/Banzai pairing and partly because it's one of those things that's fun to argue about.
** In ''Disney/TheLionKingIISimbasPride'', isn't it so convenient that Kovu isn't really Scar's son, making it perfectly okay for him to get it on with his cousin? This was a last minute change as Kovu was originally Scar's biological son with a StrongFamilyResemblance before the writers realized the [[KissingCousins minor case of incest in point]].
[[/folder]]

[[folder:Films -- Live-Action]]
* The Spanish movie ''[[http://www.imdb.com/title/tt0133363/ Los Amantes Del Círculo Polar]]'' extends this trope from FlirtyStepSiblings in that Otto's divorced father marries Ana's widowed mother first when the two children are just ten years old. Then, as they are living together in the same house, a teen romance gradually develops between Ana and Otto into a full-blown sexual relationship which, however, they manage to keep completely secret from their parents/stepparents to the end. Curiously, the possibility that the relationship between two opposite-sex stepsiblings could ever go beyond familial love never does seem to occur to either of their parents/stepparents or much of anyone else, which is why the two are able to conceal their nightly liaisons from them so easily.
* A ''very clumsy'' Western example: ''Film/AtorTheFightingEagle'' (the first ''Ator'' film; ''[[Series/MysteryScienceTheater3000 MST3K]]'' fans might be more familiar with its sequel ''Film/CaveDwellers''). Ator, the titular swordsman, falls in love with what he ''thinks'' is his blood sister and when he asks their father permission to marry her, the father happily reveals that he is in fact, adopted. (Instead of, you know, being ''totally squicked out'' by the idea that he would love his blood sister in the first place).
* Richie and Margot in ''Film/TheRoyalTenenbaums'' are a somewhat more realistic treatment, as their relationship is considered inappropriate despite everyone knowing that Margot is adopted. Interestingly, Anderson had originally intended for this to be an [[AvertedTrope aversion]], based on a [[WriteWhoYouKnow real-life friend]] who was [[BrotherSisterIncest in love with his own sister]]. It was changed late in the process when Anderson came up with the RunningGag of Royal introducing her to everybody he knows as "my ''adopted'' daughter, Margot Tenenbaum."
* ''Film/{{Clueless}}'', where Cher realized at the end of the movie that she had been unconsciously harboring feelings for her former stepbrother. Their parents got married when they were both teenagers and later divorced, so technically they weren't related at all at that point.
* In ''Film/CruelIntentions'' the main character Sebastian is obsessed with his stepsister Kathryn, who uses the promise of sex to get him to help her with her revenge.
* This was brutally parodied in ''Film/NotAnotherTeenMovie'' when their Kathryn expy constantly tries to seduce her brother.
-->'''Jake:''' That's disgusting. You're my sister!\\
'''Catherine:''' Only by blood!
* ''Film/TheWrongBox'': Parodied in the Dudley Moore film: when the protagonist laments that cousins cannot marry, his love interest replies that she was adopted. After a moment's reflection, he responds: "Really? I was adopted too."
* Zhivago and Tonya, who end up married, in ''Film/DoctorZhivago''.
* The French movie ''Film/TheFlowerOfEvil'' has a pair of stepsiblings who have had the hots for each other for years. Nobody really thinks this is squicky, in fact some of the family seem to wish they'd just get on with it.
* In ''Film/BigTrouble'', Matt Arnold and Jenny Herk's parents meet through each other, have sex, and eventually get married. Meanwhile, their relationship is somewhat implied to be a bit more than platonic.
* In ''Film/{{Teeth}}'', Brad likes his stepsister a little too much. She doesn't know it for most of the time and is horrified when she finds out.
* In ''Film/LoneStarStateOfMind'', Earl and Baby were already dating when his mother and her father decided to get married. Since they're not actually siblings, they don't see anything wrong with their relationship. A few people still harass them about their technical incest.
* In the Hallmark movie ''What the Deaf Man Heard'', the main character's love interest mentions to him in passing that her {{Jerkass}} brother is the one who revealed to her that she was adopted. Although this is never brought up again, the reason for its inclusion in the script becomes apparent when it comes to light that [[spoiler: the main character is the illegitimate son of her adoptive father, and thus the heir to the family fortune.]]
* The film ''Film/MaryShelleysFrankenstein'' plays this up far more than the novel (see below). This culminates in a rather strange line as Victor and Elizabeth are about to make love on their wedding night.
--> '''Elizabeth:''' Brother and Sister no longer...
* Subverted in the 1991 French Film "Toto le Héros" (Toto the Hero) The main character is convinced as a young boy (about 10) that he was switched in the hospital with his neighbor shortly after they were born. He uses this to rationalize his crush on his sister. They may or may not have done anything sexual at that age.
* Infamously [[InvertedTrope inverted]] in ''Film/ReturnOfTheJedi'' with Luke and Leia, with the revelation that they were the siblings... one movie after Leia kissed Luke on the lips in ''Film/TheEmpireStrikesBack''. [[http://weknowmemes.com/2013/10/the-exact-moment-luke-and-leia-found-out-they-were-twins/ Their actors' reactions tell the whole story.]] Leia's assertion that "Somehow, I've always known" just makes this worse.
* Actually brought up (in a non-sexual way) during ''Film/{{The Avengers|2012}}'': Thor is angry when the other Avengers start talking about how evil Loki is, claiming that "he's still of Asgard, and my brother." Upon hearing just how many people he'd killed in the past few days, he seems to take this back, saying, "He's adopted."
* In ''Film/MrNobody'', Anna and Nemo are schoolmates who become stepsiblings in their mid-teens and fall in love, much to their parents' dismay. Interestingly, Nemo is shown to have three love interests and Anna is [[spoiler: depicted as being the right girl for him]].
* In the 1955 French movie ''Le fils de Caroline chérie'', Conchita knows that Juan was adopted at a young age and uses it to rationalise her feelings for him. However, Juan doesn't learn this until a third of the way through, and the youngest sister Pilar doesn't learn this until the end of the film... and they're quick to jump to talking about marriage after this reveal.
* The ''Film/AlvinAndTheChipmunks'' films changed the Chipettes so that they end up adopted by Dave instead of Miss Miller. This means that they're legally the adopted siblings of the Chipmunks while still being their love interests.
[[/folder]]

[[folder:Fairy Tales]]
* In "[[http://www.surlalunefairytales.com/authors/aulnoy/1892/princessbelleetoile.html Princess Belle-Etoile]]", Princess Belle-Etoile is found with her two brothers and her cousin as a baby and they are all raised by the same couple. Princess Belle-Etoile and her cousin fall in love and find it very strange that she doesn't react to him the way she does to her brothers. Then, they learn they are foundlings and set out, and so find that they are only first cousins, and marry.
[[/folder]]

[[folder:Literature]]
* Antigone and Haemon in ''Theatre/{{Antigone}}''. Of course, Antigone's mother is also her grandmother, so being into Haemon seems almost normal by comparison.
* ''Literature/{{Frankenstein}}'' (1818). The same was true, but considerably more (sexually) explicit, in TheFilmOfTheBook, ''Film/MaryShelleysFrankenstein''. At least kind of; Elizabeth was raised by Victor's parents, but there seems to have always been a kind of barrier between the two thinking of each other as siblings, probably because their family always ''wanted'' them to get together as adults. Note that they may be [[KissingCousins biological cousins]] depending on which edition you read.
* Heathcliff and Catherine Earnshaw in ''Literature/WutheringHeights'' (1847), Heathcliff being a fostered foundling. On the other hand, it's been speculated that (like many "wards" of the era) he might really have been an illegitimate son of Catherine's father, which would make them half-siblings.
* Subverted in Creator/DaveBarry's novel ''Big Trouble''. Matt and Jenny fall in love throughout the events of the book, but when their parents get together, they decide it's just too weird and break it off, but remain close friends.
* Played with in Augusten Burroughs' 'Sellevision' where two main characters fall in love and bang, then find out they are related [[spoiler: but they're actually not... whew]].
* Creator/JimButcher's ''Literature/TheDresdenFiles'': Harry Dresden and his [[EnigmaticMinion mysterious ex-girlfriend Elaine]] were adopted by their EvilMentor when they were small children and raised as brother and sister. Once puberty struck, they took their relationship in the expected direction. Granted, "small children" here is about ten, at least in Harry's case, which is more than old enough to avoid feeling like brother and sister.
* Inverted in Creator/OrsonScottCard's ''[[Literature/EndersGame Speaker for the Dead]]'': Ender's speaking makes it public knowledge that [[spoiler:Miro and Ouanda]] are, in fact, blood half-siblings. Given that the alternative was that [[spoiler:Miro's dad's debilitating disease was profoundly different from ''every other case in recorded history'' in that it didn't start by obliterating his reproductive capabilities]], you'd think somebody would have worked it out sooner, but [[spoiler:the entire colony is profoundly Catholic and so the idea of his wife stepping out on him to have five or so kids just never crossed anyone's mind.]] It's pretty sad.
** [[spoiler:Almost no one else knew about the disease until the man's death. His wife hid the records.]]
* In the Lord John Gray spinoffs of Diana Gabaldon's ''Literature/{{Outlander}}'' series, the main character finds out that his new stepbrother was a guy he used to sleep with. It's awkward, but that apparently doesn't last long, and they're promptly back together. Which is ok, except for the fact that they're living in the 18th century and hence have the appropriate [[EternalSexualFreedom awkwardness]]. (There was CharacterDevelopment in there somewhere, but it still managed to {{squick}} some readers…).
* P. D. James's crime novel ''DeathInHolyOrders'' featured a half-brother and sister who discovered each other's existence as adults and start a casual sexual relationship. The sister, in particular, behaves as if it's no big deal, and makes the excuse that it's not like they're ''full'' siblings. Of course.
* The Cullens in Creator/StephenieMeyer's ''Literature/{{Twilight}}''--though all the "children" met as adults, and weren't raised together.
* Elizabeth Peters' book ''Literature/TheLoveTalker'', the main character Laurie is aware of un-sisterly feelings towards the half-brother she did ''not'' grow up with and barely knows. [[spoiler:she eventually learns that her supposed brother is actually an adopted child. Based on some of his earlier actions, she concludes that he knows this and has romantic intentions toward her too which is terrific]] saying something about how it's good to know, because she'd draw the line at BrotherSisterIncest.
** Another Elizabeth Peters' example comes from her AmeliaPeabody series: Amelia's son Walter "Ramses" Emerson is attracted to his adopted sister Nefret pretty much from the moment he meets her, but it takes Nefret a long time to see Ramses as anything other than an AnnoyingYoungerSibling.
* This kind of thing may be an AuthorAppeal in Creator/TimPowers' novels, when it isn't straight up BrotherSisterIncest.
** ''Literature/ExpirationDate'': there is a passing reference to the protagonist's twin sister trying to force him into bed.
** ''Literature/LastCall'': the [[FisherKing protagonist]] marries his foster-sister (at that point the full-fledged earthly representation of a syncretic moon goddess). Mythologically speaking, they can't really win the game (as it were) without marrying; the {{Squick}} factor is potentially mitigated (or greatly enhanced) by the fact that the protagonist was fifteen or sixteen when his sister was born and at the time of the novel hasn't seen her since she was a child.
** ''Literature/TheStressOfHerRegard'': after the death of his wife, the protagonist is MistakenForMurderer by her AngstySurvivingTwin. She later comes to accept that he is innocent of the crime, and for years they work together (and pass for) brother and sister. When at a later point they have to pass as husband and wife, there are complications.
* ''Literature/TheDarkElfTrilogy'': Wulfgar and Catti-brie, both humans and both adopted children of the dwarf king Bruenor Battlehammer, are not otherwise related. [[spoiler:It doesn't last anyway.]]
* Odd subversion in ''Literature/TheFirebringerTrilogy'': When hero Jan's father Korr flies into a rage over Jan's marriage to the healer's daughter Tek, Jan doesn't understand, until he finds out that [[spoiler:Tek's father was not the healer, but actually Korr. This in turn sends Jan into something of a Heroic BSOD, and when he sees Tek again and tells her what he has learned, they agree to renounce their marriage, believing themselves to be half siblings. Just before they actually do so, Jan's mother steps in and reveals that the pair aren't actually related by blood--Korr is not Jan's father after all.]]
* Both played straight and subverted in ''Literature/OneHundredYearsOfSolitude''. Rebeca marries José Arcadio, as Rebeca technically isn't related to him, but their parents kick them out of the house anyway. The second example is a spoiler for the end: [[spoiler:Amaranta Ursula (seventh generation) and Aureliano (the second) Babilonia get married under the pretense that they aren't related, but then Amaranta Ursula gives birth to a child with a pig's tail, he is eaten by ants, and Aureliano Babilonia realizes that Amaranta Ursula is his aunt.]] ItMakesJustAsMuchSenseInContext
* Literature/JackHarkaway, a popular Penny Dreadful hero, fell in love and eventually married his adopted sister. They had a kid together.
* There's a Harlequin/{{Mills and Boon}} medical romance called something like ''A Wife for the Baby Doctor'' where the eventual wife of the title is the hero's adopted sister.
* ''Literature/DoctorZhivago'': Zhivago and Tonya, as mentioned above, also hit it off in the book. Although Zhivago's [[TheDulcineaEffect eyes are set on someone else…]]
* Even though Creator/VCAndrews' works are best known for BrotherSisterIncest, it's actually more common for the heroine to end up with a man she initially believes is her brother/half-brother/cousin until it's revealed that they are not actually blood-related, making it fine for them to marry each other. The best example of this is the Literature/CutlerSeries where Dawn learns that she's actually adopted and that Jimmy is hence not really her brother; Jimmy even expresses his relief about this as he was attracted to Dawn even when he thought they were related. (And just to top this all off, Dawn's original boyfriend Philip turns out to be her ''actual'' brother who remains obsessed with her after the truth of their relations comes out to [[LoveMakesYouEvil absolutely creepy levels]]. Got to love VC Andrews' wacky plots). Other examples are Heaven's daughter Annie and apparent half-brother Luke from Literature/TheCasteelSeries, Melody and apparent cousin Cory from the Literature/LoganSeries (okay, it turns out they're [[KissingCousins still blood-related]] but only as second cousins, which makes marriage between them legal), and Rain and apparent brother Roy from the Literature/HudsonSeries (although they don't end up together, and there's that thing about Rain's own blood brother being attracted to her too--she doesn't end up with him either, thank goodness).
* In the Harper Connelly series written by Charlaine Harris, Harper develops romantic and sexual relationship with her stepbrother Tolliver that eventually leads to them becoming engaged, much to the shock of their relatives. Making it especially squicky, they have two mutual half-siblings from his father's marriage to her mother.
* Georgia and Shaun, from Mira Grant's ''Literature/{{Newsflesh}} Trilogy''. Heavily implied in ''Feed'', the first book, and [[TheReveal confirmed]] in ''Deadline'', the second.
* In Creator/RafaelSabatini's ''Literature/{{Scaramouche}}'', Andre-Louis and Aline are raised together, and Andre-Louis refers to her as a "sort of sister". They are completely in love.
* ''Literature/ASongOfIceAndFire'' has this a lot, mostly due to the Westerosi custom of fostering their children. Romances between foster-siblings aren't considered anything out of the ordinary and are often encouraged, as it makes the ArrangedMarriage that comes after [[PerfectlyArrangedMarriage a lot easier]] to go through with. Kids are usually tweens by the time they're fostered out, and view their foster-siblings as peers and friends, not siblings:
** Petyr Baelish played "kissing games" with both his foster-sisters, Catelyn and Lysa Tully. He eventually fought an (unsuccessful) duel for Catelyn's hand--[[spoiler:and later married Lysa.]]
** Tyrion Lannister invokes this deliberately by sending his 9-year-old niece Myrcella Baratheon to live with her fiancé, [[spoiler: 11-year-old Trystane Martell]], years before they will be old enough to marry.
** Quentyn Martell mentions that there was a general expectation that he would marry his foster-sister, Gwynth Yronwood. [[spoiler: He doesn't, but it would probably have been better for him if he had…]]
** Theon Greyjoy--although they never interact in-series, he remarks several times that he'd hoped to marry his foster sister Sansa Stark, even though he knew it would never happen. [[spoiler: Later, when he takes Winterfell, he thinks that, if she weren't in King's Landing, [[AndNowYouMustMarryMe he might have forced her to marry him]] to secure his hold on the castle.]] Made somewhat {{squick}}y since, the last time he saw her, he was 19 and she was 11, and they're only two 2 older now.
* A VillainousIncest couple who actually produced a child in ''Literature/ABrothersPrice'' were considered [[BrotherSisterIncest siblings]] by the culture--marriages consist of one man, maybe two if they're lucky, and a band of sisters who are themselves descended from sisters, and all offspring from this marriage are considered to be siblings--but genetically are [[KissingCousins cousins]]. The social consideration overrode this trope and the couple were regarded with disgust and horror regardless of genes. The trope itself was used to point out that their child wasn't as poorly off as she could have been.
* In the ''Hetty Feather'' series by Jacqueline Wilson, Hetty's most consistent love interest is her former foster brother Jem. In the final book, ''Emerald Star'', he proposes to her and when she protests that she is his sister, he tries to convince her that they are allowed to love each other because they are not blood relations. [[spoiler:Hetty rejects him anyway as she is leaving to join the circus.]]
* In the young adult novel ''Cluing In'' by Jo Ramsey, main character Jamey Mandel's parents, Tamara and Sam, are stepsiblings; Tamara's father Victor is married to Sam's mother Martha. Somewhat subverted in that Tamara got pregnant with Jamey (at age 17) before she and Sam realized their parents even knew each other, and before Martha got pregnant by Victor. Victor and Martha got married before Tamara and Sam did, though.
%% * ''Literature/TheMortalInstruments'': Jace Wayland and the Lightwoods, [[spoiler: him and Clary after all.]]
* Things get very complicated in Ursula K [=Leguin=]'s "O" short stories: the people of O have four-person marriages called ''sedoretu'', but because humanity is divided into two categories (moieties) which you inherit from your mother, each man is only allowed to sleep with one of the women (and vice versa)--your partner must be from the other moiety. If you're a child of one partnership, the children of the other are your "germanes", and when you grow up, you're allowed to marry and sleep with your germane (who, after all, isn't even a half-sibling, but will have grown up living in the same house). A full brother and sister can also marry, but they won't be in the same sexual pairing as they'll have inherited the same moiety from their mother. Whether or not it's considered appropriate to marry your germane or sibling seems to vary depending on where you live. ItMakesSenseInContext--if you concentrate. Le Guin was the daughter of an anthropologist and it shows.
* In ''Literature/MidnightsChildren'', [[spoiler:Saleem]] tries to invoke this when confessing his love to his sister. (He was SwitchedAtBirth, you see.) [[SubvertedTrope She doesn't go for it]], and in fact punishes him by [[spoiler:abandoning him to the army after they become orphans]].
* In Creator/AgathaChristie's ''Ordeal by Innocence'', the Argyle children are all adopted and therefore have no blood relation despite being raised as siblings. Throughout the events of the books, it's made quite clear that Micky and Tina has romantic feelings for each other, and it is implied that they would eventually marry.
* ''LightNovel/BrothersConflict'' is a ThemedHarem involving thirteen stepbrothers ([[{{Lolicon}} the oldest being 31 and the youngest being 10]]). As if that wasn't enough [[spoiler: it's revealed that Ema was actually adopted and her father is not her biological one]] in order for the creators to continue shouting "IT DOESN'T COUNT!" as loud as they can.
[[/folder]]

[[folder:Live-Action TV]]
* ''Series/{{Eastenders}}'': Dennis and Sharon.
* ''Series/TheFosters'': Callie and Brendan are foster siblings and they follow this trope to a T; they even [[SecretRelationship date secretly at one point.]] Because they're the FanPreferredCouple, the show-writers do everything within their power to prevent Callie's adoption papers from being finalized and making their sexual tension officially incestuous.
* ''Series/{{Ultraman}}'':
** Most of the Ultra Brothers are this. However, it is explained that they are all distantly related to each other in some way, usually as part of extended families. Zoffy, for example, is the King's grandson, and Ultraman Ace is one of Ultraseven's cousins.
** This trope is played around with Ultraman Ace and Taro--whilst Ace is an orphan who was adopted by Taro's family, they have such a close brotherly relationship that they might as well be considered blood brothers.
** This is averted by Ultraman Leo and Astra, who are blood brothers by all accounts. This status is clearly emphasized by Astra's tendency to yell "''NII-SAN!''" to Leo whenever he is in danger or being beaten down.
* Stepsiblings Boone and Shannon in the first season of ''Series/{{Lost}}''.
* Subverted for all it's worth on ''Series/ArrestedDevelopment''. [[spoiler:Cousins George Michael and Maeby are attracted to each other and George Michael clings to any hope that Maeby isn't his Aunt Lindsay's daughter. When they find out that there's a chance she's been adopted, they go to second base... then they find out that she ''is'' Lindsay's daughter. As a result, Maeby begins dating a boy from school--Steve Holt. Meanwhile, Steve decides to find the father he never knew, who turns out to be GOB, Maeby's uncle. As a result, they break up. Then Maeby's mother Lindsay turns out to be adopted. Lindsay promptly starts hitting on George Michael's father, who is completely freaked out after thinking she was his twin for 37 years.]]
** [[spoiler: And then, "in a kneejerk act of revenge", Michael's brother GOB decides to hit on his adoptive sister Lindsay.]]
** Lampshaded with the in-series movie ''Les Cousins Dangereux'', a stereotypical french movie about cousins in love. When it's finally re-made for American audiences, the narrator explains that "the studio [...] had hoped to avoid controversy by artlessly explaining that the two leads were not biological cousins" but it didn't stop the protesters from picketing the premiere.
*** A callback joke has narrator Ron Howard remind the audience that George Michael and Maeby might not be ''actual'' cousins.
* Despite the number of possible pairings and the age of the oldest kids when their (step) parents first met, not just subverted but ''entirely avoided'' in ''Series/TheBradyBunch''. It is, however, ''constantly'' mentioned in any parody of the show. It's also a subplot in the second [[Film/TheBradyBunch Brady Bunch movie]], when they think their parents didn't actually get married.
** In a weird Meta twist, nearly every ''actor'' on the show [[CastIncest hooked up with one or more members of their TV family]] at one point or another.
* The Venturis and The Mcdonalds in ''Series/LifeWithDerek'', with Derek Venturi and Casey Mcdonald being the main characters who have a full bucket of BelligerentSexualTension.
* Likewise completely avoided in the ABC sitcom ''Series/StepByStep''. Though considering how... unBrady-like their relationships were amongst themselves, this is somewhat more understandable.
* Not avoided in an episode of ''Series/CSIMiami'', where the father of a murdered woman's baby is discovered to be her brother: turns out they met and became stepsiblings when their parents married (and the two kids were 18 at the time) and one thing led to another.
* Nate from ''Series/SixFeetUnder'' has an affair with his newly introduced stepsister. Nate is neither squicked by this fact nor the fact that he's screwing around on his wife with someone he's known for less than a month. This, plus Nate's [[{{Narm}} trope-naming Karmic Smackdown]] had Nate's portrayer, Peter Krause, not happy at all.
* On ''Series/TwoAndAHalfMen'', Charlie becomes sexually involved with the daughter of his mother's fiancé, repeatedly pointing out that she will only be his stepsister.
* Arthur and Morgana in ''Series/{{Merlin|2008}}''. Morgana was raised as the ward of Arthur's father Uther. No expressed romantic interest on either side, but definite sparks and ShipTease. Then in "The Crystal Cave," it is revealed that [[spoiler:they ''are'' blood siblings]]! Though technically, that's been an ItWasHisSled for several hundred years now.
* Soap operas do this sometimes, particularly ''Series/DaysOfOurLives'', where almost everybody is related to everyone else somehow (puzzling out the Brady/Horton/[[spoiler:Kiriakis[=/=][=DiMera=]]] family tree is so complicated that NBC even runs a commercial spot with star Ali Sweeney claiming she can't figure it out). Lately, Max Brady (adopted son of Caroline and Shawn, brother of Roman, Bo, Kayla, and Frankie) has dated two of his female nieces, Stephanie (daughter of Kayla) and Chelsea (daughter of Bo), and nobody has found this the slightest bit strange or squicky. Of such fine technicalities are the constantly-churning relationships of soap opera characters kept acceptable to the MoralGuardians.
* On ''Series/AsTheWorldTurns'', it's signature supercouple, Holden and Lily, are actually uncle and niece, because her mother was adopted by his family. The ickiness is undercut by the fact that she did not grow up knowing him as her uncle--she and her twin sister, the product of their mother's rape, were themselves given up for adoption.
* Not canon, but this is the rationale people who 'ship Brooke and Sam of ''Series/{{Popular}}'' together use. That and the fact that they were about 16 when their parents married.
* On ''Series/BattlestarGalactica2003'', Kara Thrace and Lee Adama are not biologically related, but they consider the same person to be their father (Bill Adama) and Kara was engaged to Lee's dead brother. Their interactions wildly vary between very close, occasionally juvenile best friends and a highly-charged sexual relationship.
** Also any sexual relations between the seven models of humanoid Cylons, such as Boomer/Cavil and Caprica/D'Anna, as well as the failed attempts at Cylon breeding offscreen.
* Adrian and her step brother Max in ''Series/SecretLifeOfTheAmericanTeenager''.
* In the season two premiere of ''Series/{{Reaper}}'', Sock, once he gets over the shock of a stranger living in his mother's house, instantly lusts after his hot Japanese stepsister whom he just met when they were both adults, and did not grow up together. The problem is, she just wants a genuine sibling relationship between them, and is completely oblivious to his attraction (until it gets really, ''really'' {{Anvilicious}}).
* On ''Series/DarkAngel'', Max and the rest of her X5 unit consider each other siblings because they were "raised" together. Zack falls in love with Max, and it {{Squick}}s her out. She wasn't too sanguine about the idea of being breeding partners with Alec, a clone of her brother Ben, either.
* ''Series/{{Dexter}}'': Although Dexter and Deb are not in the least bit involved, there was an instance where when Deb got angry with Masuka for not inviting her to Dexter's bachelor party. He said that it was men only, unless she had wanted to be talent for the evening. Deb says that is gross as they're siblings, to which Masuka replies "not by blood". Dex just puts on his killing face in response. [[spoiler:Turns out Dexter may actually be Harry's bastard son, which would make Dexter and Deb half-siblings]]. Deb also dated [[spoiler: Dexter's biological brother, the Ice Truck Killer]] in the first season, although she was [[IncestIsRelative unaware of the connection at the time]]. Her own psychologist tries this excuse while suggesting that Debra's love for Dexter may be more than just sisterly, using this trope as a justification. She later fell in love with Dexter totally, which became a key plot point late season six onwards.
* ''Series/{{Roseanne}}'':
** Darlene and David's relationship didn't start this way, but it became more and more the case as the series went on. When David was "adopted" (taken in) by the Conners, Roseanne let him know he could move in by walking in on David and Darlene kissing and cheerfully crying to Dan, "Oh, look, honey, our kids are necking!" By the time they got married, Jackie opened the episode by saying, "I can't believe our little Darlene is marrying... our little David," Mark scolded David for asking about their birth parents when the Conners were practically his parents, and David and Darlene paid tribute to "''our'' parents Dan and Roseanne Conner" in their wedding vows.
** Another episode centers on David being creeped out that he had an erotic dream about [[spoiler:Roseanne]] because he thinks of her as his [[spoiler:mother]].
* In season 1, ''Series/VeronicaMars'' finds out that her mother and the father of her ex-boyfriend Duncan Kane were HighSchoolSweethearts who may have continued their relationship as an extra-marital affair... meaning that she and Duncan may or may not be half-siblings. This revelation leads her to pull her car over and puke on the side of the road. Luckily, the paternity test that her father has done proves that she and Duncan aren't related. A few months later, they resume their relationship. Though according to WordOfGod, Duncan was SUPPOSED to be Veronica's half-brother for real, but the network wouldn't let them put Actually-Blood-Siblings sex on the air. So it was originally meant to be a complete (and squicky) subversion of the trope.
* Justin and Rebecca on ''Series/BrothersAndSisters''. When they met they believed they were half-siblings, but when she did a paternity test it turned out that they weren't, and then they became a couple. Which is a case of the familial relationship being changed in order to facilitate the romantic relationship. Unlike that one, however, the original plan was ''not'' to have them in a relationship, but [[CastIncest the chemistry between the actors was so strong that it became impossible to not see them as a couple]].
* In ''Series/TerminatorTheSarahConnorChronicles'', as far as the rest of the world is concerned, Cameron is John's sister. The sexual tension, by the way, is ''palpable''.
* The SoapOpera ''Series/TheBoldAndTheBeautiful'':
** A ''particularly'' [[{{squick}} squicky]] example: In 2003, Ridge discovered that his father was [[LukeIAmYourFather not Eric, but Massimo]]. Meaning his half-sister, Bridget, wasn't his sister. He told Bridget and they were kissing shortly thereafter. That's bad enough on its own, but consider their history. Ridge had been in a on-off relationship with her mother for 15 years at that point. He also helped Brooke [[DeliveryGuy deliver]] Bridget in Big Bear ten years ago. He and Brooke had an affair, so they all believed ''Ridge'' was Bridget's father until she was 4. She was even named B''ridge''t after Ridge. So Ridge made out with a woman who he not only thought was his sister but also [[ParentalIncest his daughter]]. Thankfully, any Ridge/Bridget pairing [[AbortedArc didn't get too far]], but several years later, Ridge's younger "brother" Rick used the fact that they were not biological brothers as justification for pursuing both of Ridge's daughters, claiming that they were fair game since they weren't biologically his nieces. Negative audience reaction mercifully ended these stories very quickly as well.
** And a not-quite-as-disgusting-but-still-weird one, when Macy's younger brother CJ (they shared the same mother), fell in love with Macy's younger sister Kimberley (they shared the same father) and actually had to keep reminding her that despite sharing a sister, they themselves were not related.
* More than that, in the live-action ''Series/NinjaTurtlesTheNextMutation'' it was claimed that none of the turtles were actually related to each other; they just happened to be the same relative age in the same terrarium at the time. This was done so that, when a female turtle shows up later, there would be the potential for a relationship. Buuut, [[FanonDiscontinuity we don't talk about her...]]
* Subverted in ''Series/That70sShow'', in an episode where Eric's hot cousin comes to visit and tells him she's adopted, and then seduces him just to trap him into making a move on her in front of his parents. She's not adopted at all; she just wanted to pay him back for a prank he pulled when they were younger.
* Subverted in the 2009 TVB drama ''Born Rich'': [[spoiler:The family's "long-lost" half-brother is actually dead and the "brother" that they have been interacting with is actually a twisted con man who stole the dead man's identity and wormed his way in. He develops a romantic obsession with his "sister" to the point that he rapes her. Needless to say, when she discovers the truth about her "brother"'s identity and his actions, her previously conflicted feelings turn into hatred and revenge]].
* In ''Series/{{Wonderfalls}}'' after [[spoiler:Mahandra and Aaron]] sleep together she freaks out because they grew up together, although they're not actually adopted siblings.
* PlayedWith on ''Series/ThirdRockFromTheSun'' when the Solomons attend a family reunion pretending to be long-lost relatives. Tommy falls for one of the other guests, but she freaks out because he's supposedly her cousin. Harry, meanwhile, has been catching up on family gossip and reveals that she was adopted, which Tommy expects will fix things. It doesn't. All three male Solomons also occasionally show sexual interest in Sally.
* ''Series/PrettyLittleLiars'': Stepsiblings Jenna Marshall and Toby Cavanaugh.
-->'''Aria:''' Toby and Jenna had a relationship.\\
'''Spencer:''' Way beyond step-siblings.\\
'''Aria:''' Yeah, they… were involved.\\
'''Emily:''' Romantically?\\
'''Spencer:''' I doubt I'd call it ''romantic''--I doubt she had much of a choice.
::: Because AllAbusersAreMale and DoubleStandardRapeFemaleOnMale, it's assumed that Toby was the [[SexualExtortion perpetrator]]. He wasn't.
-->'''Jenna:''' You need to be home. Where you're safe.\\
'''Toby:''' You could chain me to this porch and I'd still never touch you like that again.
* ''Series/{{Smallville}}'' featured an example [[spoiler: on the alternate-universe Earth Two: Tess Mercer is having sex with her adopted brother, Clark Luthor.]] When you think about it, the boy was adopted, and the girl was never taken care of by her father. So even if both have Lex as a brother in one way, they are hardly siblings in any way.
* Perhaps the most sick and overly complicated example imaginable on ''Series/{{Passions}}''. Chad who is biracial comes to town and eventually dates Whitney the son of Eve and TC (the only black family in town). Chad is for several years hinted to be the son of Eve and her white lover Julian from before she was married. Later Chad and Whitney have a baby together and the revelation comes out that they are half-brother and half-sister and their baby was born from incest. Later is revealed that Chad is not really Eve and Julian's long lost son. It turns out Julian's father Alistair had raped Eve's adopted sister so yay Chad's son is not a product of incest but on the other hand Chad is a product of rape. Even later it is revealed that Chad is having a gay relationship on the down low with a guy named Vincent... who turns out to be Eve and Julian's hermaphroditic long lost child for realsies this time... oh and he's a serial killer and a rapist to boot. So yeah Chad didn't sleep with his half-sister... but he did sleep with his girlfriend's half-brother who was also his own half-nephew.
* A very strange example in ''Series/SixteenAndPregnant'' (and spin-off ''Teen Mom''): couple Catelynn and Tyler are stepsiblings, because Catelynn's mom April and Tyler's father Butch are married. Butch and April met and married ''after'' their children started dating.
* Iris and Barry from ''Series/{{The Flash 2014}}'' have been raised together from a relatively young age and Barry thinks of Iris's dad as a second father. Despite pretty much being his foster sister, Barry still has had a crush on Iris for a while. Perhaps in an attempt to lessen the potential squick factor, its explicitly stated by Joe that Barry had a crush on her before he came to live with them and watched Barry be in love with her before he knew what love was. Nobody on the show seems to mind their attraction to each other, either.
* Any episode of ''Series/JerrySpringer'' that claims that parents and children, siblings, or cousins are in love likely falls into this trope.
* The TV movie adaptation of ''Literature/SeedsOfYesterday'' concludes with Bart and his adopted sister Cindy falling in love and getting married. Presumably, the writers took the AlternativeCharacterInterpretation of both of them in the book that interprets their constant arguing as BelligerentSexualTension.
[[/folder]]

[[folder:Music]]
* Dennis Warner's song [[http://www.youtube.com/watch?v=W7x1ETPkZsk I'm My Own Grandpa]] plays this for laughs.
* Lord Melody's ''Shame & Scandal'' too. [[GermansLoveDavidHasselhoff Huge in France]].
* Played straight, but in a twisted way in ''[[http://www.chivalry.com/cantaria/lyrics/johnny_be_fair.html Johnny Be Fair]]'', by Buffy Ste. Marie. Video [[http://www.youtube.com/watch?v=6RdIg431a8w&feature=related here]].
[[/folder]]

[[folder:Music Videos]]
* In ''Music/{{Vocaloid}}'':
** Rin and Len Kagamine, who fans are debating over whether or not they are twins... despite the fact they have the ''same last name''. Some claim that they are merely only [[GenderBender genderbents]] of each other to avoid having their fanfictions labeled as {{Twincest}} (and thus it's {{selfcest}} instead), while others are eager to embrace the twincestiness that comes with them.
** To a lesser extent is the genderbents of the vocaloids (i.e. Mikuo, Kaiko, Gakuko, Luki, Ted); the fandom can get away with pairing them up because they are simply gender reversals of the official vocaloids and therefore are not canon siblings.
** In an attempt to placate the detractors, the creators declared that Rin and Len were literally mirror-versions of each other, so probably somewhere between HalfIdenticalTwins and OppositeSexClone. Of course, considering that all the Vocaloids are ''computer programs''...
[[/folder]]

[[folder:Puppet Shows]]
* Shiro and Lamia in ''Series/StarFleet''. Lamia was sent to Mars from the Planet Esper to escape Imperial Alliance attack, where Professor Hagen, Shiro's father, raised her in secrecy.
[[/folder]]

[[folder:Video Games]]
* ''VideoGame/BaldursGate'':
** Fans frequently debate whether a relationship between the PC and [[spoiler:Imoen, both Children of the dead god Bhaal]], would "count" as incest. Those who favor the relationship usually point out that the PC is often a different race from her, and that canonically they are known to not have the same mother, so that their main connection is definitely not any mortal source. (This is even brought up in the expansion ''Throne of Bhaal'' in a discussion between her and one of the other party members; Viconia suggests she should serve the main character in every way he desires for all that he's done for her, and why it shouldn't be a problem. [[spoiler:Imoen]] balks at the thought and finds the idea disgusting... and then turns the question back on Viconia, who's also been canonically saved twice by the protagonist and ''is'' a romance option). Ultimately irrelevant, as she isn't a romantic option in the game... unless you mod it. And the only mod currently available and semi-complete is not very good.
** The same argument is made for the female PC and Sarevok, who are also Children of Bhaal from different mothers. It's a little easier to defend, since [[spoiler:''Throne of Bhaal'' makes it clear that Sarevok no longer has the Essence of Bhaal, and that was how he was related to her]]. Once again, it's irrelevant since he's not a vanilla romance option. Though his mod romance ''is'' better than [[spoiler:Imoen's]], at least.
* In the ''VideoGame/MegaManLegends'' universe, Rock (Mega Man) is ''literally'' Roll's adopted brother, yet romantic hints exist. Fans [[{{Fanwank}} debate]] whether the [[VideoGame/MegaMan original series]] Rock (Mega Man) having a relationship with Roll would count as incest, as their original incarnations are both robots and no genetics are involved, despite being "siblings" created by the same man. Roll's battle with Copy Roll in ''VideoGame/MegaManPoweredUp'' supports this trope as Roll's copy says that she'll confess Roll's feelings to Rock. ''Anime/MegaManNTWarrior'' Rock and Roll have no familial relation at all.
* ''VideoGame/TalesOfLegendia'', in which Senel and Shirley pretend to be brother and sister (arguably, they ''do'' rather act as though they are, but they certainly don't resemble the other in the slightest, and have different surnames, to boot) until they are exposed by the main villain as not being related at all--in fact, each of them belongs to a different ''race'' altogether. Not too long after this, Shirley confesses to Senel that she is in love with him. They presumably end up engaged via the Rite of Feriyen by the end of the Main Quest... although afterward, the other characters note that the relationship between them doesn't seem to have changed much at all (they even get new titles to reflect this; Senel obtains "Still A Brother" and Shirley obtains "Sister Girl").
* Inverted in ''VideoGame/FinalFantasyVIII'': When Quistis [[LaserGuidedAmnesia suddenly remembers]] that [[spoiler:she was raised in an orphanage with Squall]] she stops hitting on him. In fact, [[spoiler: Selphie and Irvine are the only ones who actually remain inside their raised-together group for romance. Everyone else from the orphanage looks outside the group for romance, as]] Zell hooks up with [[NoNameGiven Library Girl]] and Quistis gets shafted.
* ''VideoGame/FinalFantasyII'' mostly contains only hints of love interests but the NoExportForYou novel does have Maria harboring feelings for her adopted brother and the story's main character, Firion.
* The plot for the Kingdom of Caerleon in ''VideoGame/{{Brigandine}}'' involves [[spoiler:King Cai falling for his sister, who turns out to have been adopted]].
* The Prince and [[BodyguardCrush his bodyguard Lyon]] in ''SuikodenV'', as she's an orphan raised by his father.
* ''VideoGame/FireEmblem'':
** The series tends to prefer the [[BrotherSisterIncest full-blooded version of this trope]], but apparently decided to go the NotBloodSiblings route in ''Radiant Dawn''... ''twice''. Once with [[spoiler:Micaiah and Sothe]], and also with [[spoiler:Elincia and Geoffrey.]] In both cases, they end up married at the end if they have an A-support with each other. [[spoiler:Micaiah and Sothe]] is a combination of this and reversed WifeHusbandry. Due to her long life span she raised [[spoiler:Sothe]] from when he was a kid, though it could be argue that she viewed him as a little brother since physically she is only in her mid to late teens. Interestingly, they are the only characters who start out with A support for each other.
** Near the end of the first half of ''[[VideoGame/FireEmblemJugdral Genealogy of the Holy War]]'', King Trabant of Thracia kills Cuan and Ethlin and takes their daughter, Altenna, to raise as his own. She ends up falling in love with Trabant's biological son Areone. There's also a [[KissingCousins bit of the full blooded version there either]]: Areone is a descendant of Dain, and Altenna is of Noba... Dain and Noba were Brother and Sister. Note that this was a little over a hundred years ago.
** Doable in ''VideoGame/FireEmblemFates'' if Corrin marries any of his/her siblings from Nohr, since they were merely raised together and not biologically related [[spoiler: or his/her Hoshidan siblings, since it turns out they're not related either.]]
* Emma Emmerich, in ''VideoGame/MetalGearSolid2'', has a thing for her big brother Hal "Otacon" Emmerich. Turns out that they're really just stepsiblings; they have the same last name because Hal's dad adopted Emma after he married her mother. The sexual relationship which developed between Hal and Emma's mother, however, adds an extra layer of {{Squick}} to the situation.
* The Alex and Luna, the hero and heroine of ''LunarTheSilverStar'', grew up together after Luna was taken in by Alex's parents as an infant. The game makes it obvious that they are destined to be together, and no one in the entire game, even Alex's parents, is anything other than happy for them.
* A non-{{Squick}} example for ''VideoGame/SuperRobotWars'': the [[spoiler: [[VideoGame/SuperRobotWarsAlpha Kobayashi sisters Aya and Mai]]]] are revealed to be this. Both were originally test subjects, but their "father" [[spoiler: Kenzo]] took them in as his daughters in the hopes their exceptionally potent PsychicPowers could complement each other for the [[CombiningMecha combining]] SuperRobot SRX.
** A similar non-{{Squick}} instance for Joshua Radcliffe and Cliana Rimskaya of ''VideoGame/SuperRobotWarsDestiny'': Cliana was adopted by Joshua's father and throughout the game, the two treat each other LikeBrotherAndSister, except Joshua is sometimes called out for his BigBrotherInstinct by insisting Cliana stay away from the battlefield. Then again, when your adoptive sibling has a slightly, unstable SplitPersonality, you'd probably do what Joshua does.
* ''VideoGame/VandalHearts 2'': In a BittersweetEnding (by letting your childhood friends die), you make good on the promise you made to Clive to take care of Rosaly, your adopted sister, and the ending is that she gave birth to your child. In a semi-justification, Joshua (main character) was adopted when he was almost to his teens, and was separated from Rosaly for a long time over the course of the plot.
* Yuri and Kira from ''VideoGame/InfiniteSpace'' insist that they are siblings while everyone around them think they're just very close friends who have a thing for each other. Yuri even gets someone to do DNA tests that reveal they have no blood relationship. [[spoiler: They're ArtificialHumans created by extra-dimensional aliens and they're only "siblings" because that's the first relationship that popped into Yuri's head at the beginning. A previous scene established that he had no relatives at all to leave behind when he went into space.]]
* The curate and his [adoptive] sister in the online game ''Videogame/FallenLondon''. [[spoiler:It is possible for you to seek romance with either (or both) of them, and during the process you can find what looks like a fragment of a love letter from the sister to him.]]
* Claimed in the penultimate route of ''VideoGame/DuelSaviorDestiny'', but then undone in the actual final route. The story first claims that it's so convenient that Taiga and Mia aren't related in the resolution to her route, but in the Crea/harem route that follows it the story notes that they have a blood relation. Whether this is a subversion[[note]]Meaning they were simply wrong in the previous exchange about the matter[[/note]] or a simple retcon is unclear.
* In ''VideoGame/EnigmaAnIllusionNamedFamily'', one of the siblings is actually adopted. Learning this led one of the other siblings to {{Blackmail}} them, threatening to reveal the adoption [[spoiler:and that she's been sending money to her birth parents]]. Another sibling feels that this justifies [[spoiler:his secret attraction to her]].
[[/folder]]

[[folder:Visual Novels]]
* Hiroki and Elis in ''VisualNovel/{{Canvas 2}}''. She's actually his cousin, but she's stuck ''very'' firmly in the 'little sister' category when thinking of love interests. He writes it off as a PrecociousCrush or her just joking around despite her being persistent about it to SingleTargetSexuality levels.
* The canonical routes in both ''VisualNovel/DaCapo'' games have always been about NotBloodSiblings, though the second game strayed into a fine line between this and KissingCousins for both Asakura sisters, since the protagonist is both adopted ''and'' raised by another parent--who, in turn, is another NotBloodSiblings with Asakura grandpa.
** Which makes his surrogate son--Yoshiyuki--the adopted distant ''uncle'' of the Asakura sisters, which make his relationship with either sister one generation apart... No wait, that't not right. Hmm... Try to wrap your head around the [[TangledFamilyTree family tree of this franchise]].
* In ''VisualNovel/{{Crescendo}}'', this is also an important plot point. Ryo is living with his adopted sister, (their parents having died three years earlier) when his birth mother asks him to move in with her family. How the player answers the question is a major branch point in the story.
* Although it's pretty much one-sided, in ''VisualNovel/FateStayNight'' there's [[spoiler: Shirou Emiya and Ilyasviel von Einzbern. She is the biological daughter of his adoptive father, and has an obsession with him that is at least partially romantic. The fact that WordOfGod has openly stated that she was nearly the fourth romanceable heroine of the game ''and'' there are two separate Bad Ends where she magically makes him her slave for life (complete with heavy implications that he ''is'' 'that kind' of slave) really doesn't help]].
* A huge theme in the [[{{Utsuge}} tear-jerking]] ''VisualNovel/KanaLittleSister''.
* Akane and Yoshikazu in ''VisualNovel/{{Suika}}''. [[spoiler:Definitely doesn't go the usual way this trope normally does. You are given the choice to supposedly go that way, but then comes TheReveal...]]
* An integral part of the plot of some arcs in the ''VisualNovel/{{Tsukihime}}'' game. [[spoiler:Shiki and Akiha met when they were seven and six years old, respectively, lived together for two years, and then separated for eight, somewhat short of "growing up together." Akiha knew the whole time that Shiki wasn't her real brother, and Shiki was at least vaguely aware of it, even admitting to himself once that his protective instinct towards her didn't really seem like sibling love]]. Needless to say, that really only comes into play during [[spoiler:Akiha]]'s arc. The fact that they are not related is important in all the arcs due to the events that occurred ten years with [[spoiler:SHIKI, the real brother of Akiha]].
[[/folder]]

[[folder:Web Comics]]
* In ''Webcomic/EternalKnights'', Erica has had sexual relations with both of her adopted brothers: Jack, who she was raised with and who she calls "sisterf***er at the end of one scene, and Nicky, who she was not raised with.
* ''Webcomic/ExperimentalComicKotone'' Konstantin seems to think this is going on between Onii-chan and Kotone in ''[[http://www.tsunamichannel.com/index.php?date=2001-11-06&comic=ExCoKo Experimental Comic Kotone]]''. It isn't. What none of the characters except Kotone-chan herself and Onii-chan know is that Kotone is a RobotGirl -- the whole "little sister" thing is just a cover.
* Parodied in [[http://manga.clone-army.org/jointworks/hh/geek_ad_1.jpg this]] ad for J-List by Creator/DanKim of ''Webcomic/CloneManga''.
* Brought up by Monette in [[http://www.somethingpositive.net/sp03132009.shtml this]] ''Webcomic/SomethingPositive'' comic.
[[/folder]]

[[folder:Web Original]]
* The heads of the Website/GameFAQs group "The yusketeers" Yusiko and Yukito can't have a conversation without sexual tension showing up somewhere. Apparently people have a venn diagram just to tell them apart. Some say that the sheer sexual tension that permeates any room the two are in is enough to stun a horse.
* Devin, he guy who owns eFukt.com, says he's in a sexual relationship with his sister. He always adds that she's ''adopted'', so it's okay.
* ''Literature/ThaliasMusings'':
** Zeus and Hera. The Titans are beings of pure spirit who paired off and joined their life force to create the first generation of Olympian gods. Zeus and Hera, as well as Hestia, Demeter, Hades, and Poseidon, were created by Cronus and Rhea.
** [[WillTheyOrWontThey Athena and Artemis]]. Artemis is Zeus' biological daughter, and Athena is his ward and ex nihilo creation.
* [[FlirtyStepsiblings Mickey and his stepsister Audrey]] on ''WebVideo/{{HomeSchooled}}''.
* Deconstructed in ''Literature/{{Worm}}'' with [[spoiler:Panacea]], who is in love with her adopted sister. This is never portrayed as being any less disturbing simply because they are not biologically related, and it ends badly. [[{{Brainwashing}} Very]], [[FallenHero very]] [[BodyHorror badly]].
[[/folder]]

[[folder:Western Animation]]
* On ''WesternAnimation/TinyToonAdventures'', if Babs [[SpeciesSurname Bunny]] and Buster Bunny didn't always say "No relation" after introducing themselves, most viewers probably would have assumed they were siblings. This was parodied when they cameoed in an episode of ''WesternAnimation/{{Animaniacs}}'' about [[Literature/TheBible Noah's Ark]].
--->'''Noah:''' And you are...?\\
'''Buster & Babs:''' Buster Bunny and Babs Bunny. No relation.\\
'''Noah:''' [[ThinkOfTheCensors Let's hope not. This is a kid's show]].
* An odd example: in one episode of ''WesternAnimation/TheSimpsons,'' Homer's father briefly dates Marge's mother. Homer is against their relationship, since he believes this will make him and Marge siblings, and retroactively turn the kids into freaks "with pink skin, no overbite, and five fingers on each hand!" The two wind up breaking up, though. However, Marge later becomes Homer's ''aunt'' when Abe briefly marries Selma. Which is [[LoveFatherLoveSon even weirder]] when you take his relationship with Mrs. Bouvier into account...
* On ''WesternAnimation/{{Gargoyles}},'' the title species lives in large clans that are considered to be a single family--nobody keeps track of who their biological parents are, and thus all gargoyles of the same age group refer to each other as their "rookery brothers/sisters" and older members as their "rookery parents." WordOfGod says that real incest never occurs, though, because a) each female can only lay one egg per mating cycle and b) pheromones prevent [[KissingCousins Kissing Cousin]] relationships.
* On ''WesternAnimation/UglyAmericans,'' [[ZombieAdvocate Mark]] and [[HornyDevil Callie]] raise the latter's younger sister, [[AntiChrist Lillith]] (which admitted [[RapidAging only took about two weeks]]). Lillith then declared her intention to kill Callie and have sex with Mark in front of a stadium full of other demons. Mark, who had spent the entire episode acting like a doting, enthusiastic father, is understandably freaked out.
* On ''WesternAnimation/AmericanDad,'' Roger tricks Steve into believing that he was kidnapped from another family, causing him to [[BrotherSisterIncest kiss his supposedly-unrelated sister Hayley]].
-->'''Roger:''' Everything that happens from this point is just gravy.
* ''WesternAnimation/SymBionicTitan'': Lance and Ilana, masquerading on Earth pretend to be brother and sister at their high school. There's plenty of "moments" between them. When Lance reluctantly agrees to go to prom as a group, he decides to invite Ilana if he has to take someone (she points out she's already going with someone). One wonders how they would explain this to the others. Also, their neighbor Barb seems disappointed when she thinks that Lance and Ilana are brother and sister rather than boyfriend and girlfriend. WordOfGod though intentionally wanted to avoid romance between them mainly to avoid the obvious squick potential.
* In ''WesternAnimation/TeenageMutantNinjaTurtles2012,'' [[spoiler:[[TheLeader Leonardo]] is attracted to [[DatingCatwoman Karai]], who turns out to the kidnapped biological daughter of his adoptive father, [[TheMentor Splinter]]]].
* In ''WesternAnimation/WordGirl'', Becky was adopted into the Botsford family. Her brother TJ [[LovesMyAlterEgo can't stand her but has a crush on her superhero persona WordGirl]]. TJ doesn't know her secret, but Becky still thinks it's gross.
* ''WesternAnimation/TheLegendOfKorra'' has implications of this. Suyin says multiple times Kuvira was like a daughter to her, though she [[InformedAttribute never really shows it]], and Kuvira is engaged to one of Suyin's biological sons. It's never specified if Suyin adopted Kuvira or not however it's implied she was raised alongside her family from a young age.
* This is presumably what was intended with Two-Tone and Lucky in ''WesternAnimation/OneHundredAndOneDalmatiansTheSeries''. They're love interests despite being siblings. In the [[Disney/OneHundredAndOneDalmatians original film]] they're related ''by blood''. It's most likely the creators of the cartoon mistook Two-Tone for one of the adopted puppies.
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[[folder:Real Life]]
* At present, Japanese law allows for adopted siblings to marry, which has [[JidaiGeki feudal-era]] origins. Japanese family inheritance traditionally emphasize the transmission of family ''traditions'' rather than ''blood'', so at the time titles can only be transmitted to the title-holder biological or adopted ''son''; even nephews need to be adopted as an heir. This caused adoptions in feudal Japan to be as political as ArrangedMarriage, and many just do both--adopting a child from another family as one's heir and have the latter marry his own daughter.\\\
As an example: [[http://en.wikipedia.org/wiki/Matsudaira_Katamori Matsudaira Katamori]], ninth and the last Daimyo of Aizu and the direct boss of {{Shinsengumi}}, is an example of this ''and'' KissingCousins. He was born the seventh son of Matsudaira Yoshitatsu, the tenth Daimyo of Takasu, whose biological brother (i.e. Katamori's uncle) Takakata was already adopted out and became the eighth Daimyo of Aizu. When Aizu, again, was facing the problem of a lack of male biological issue, Katataka adopted Katamori, his biological nephew, as his son and by extension, the future ninth Daimyo of Aizu. To cement the relationship between the two houses, Katataka [[ArrangedMarriage arranged]] Katamori to marry his biological daughter, i.e. Katamori's ''first cousin by blood and sister by adoption''.
* The Roman emperor Tiberius married his stepsister Julia. Given that Julia's father Augustus and Tiberius mother had already been together when Julia was born to Augustus first wife and Tiberius was already 14 at that time, it's still more than a bit squicky. But to their credit it wasn't their idea and and didn't last long.
* A variation: prior to same-sex marriage being recognized in the U.S., some same-sex couples would [[LoopholeAbuse get around visitation restrictions in hospitals]] by having the older partner legally adopt the younger one, enabling "child" to care for "parent" or vice versa. This presented some [[CaptainObvious complications]] when it came time to actually get married.
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