[[CandyBoy http://tvtropes.org/pmwiki/pub/images/CandyBoyKanadeYukino.jpg]]
[[caption-width:300:[[HalfIdenticalTwins Fraternal Twins]] [[CandyBoy Yukino & Kanade]] [[LesYay show their]] [[SchoolgirlLesbians opinion on]] the topic.]]
->''Twincest is best!''\\
''Put your sister to the test!''

->''With a man like him (Eirika's twin brother Ephraim) around, I can see why you show no interest in suitors.''
->-- '''Innes''', [[http://www.youtube.com/watch?v=_29S1FsQcr0 from the Innes & Eirika 'A' Support Conversation]] for ''FireEmblem''

Popular culture often expects twins to share everything, including, it seems, their beds. It's a particularly common trope in SlashFic, {{Hentai}}, and [[RuleThirtyFour porn]], though it does occur in mainstream fiction often enough to be a discernable trope. It's especially common as a way of making CreepyTwins just that much more disturbing.

Note that Twincest is not necessarily homosexual: that's what fraternal twins and HalfIdenticalTwins are for. However, a great deal of the appeal to viewers is the popular fantasy of sleeping with ''two identical copies'' of a single hot person at the same time, so homosexual (or bisexual if there's a lucky third party of another gender) twincest is more often used to [[FanService titillate viewers.]] For {{Yuri Fan}}s and [[YaoiFangirl Yaoi Fans]] who became fans at least partly because they see a forbidden appeal to such relationships, Twincest supercharges that part of the appeal.

A common twist, in this and in BrotherSisterIncest in general, is for a couple to fall in love, only to find out later that they were SeparatedAtBirth. (See [[http://en.wikipedia.org/wiki/Genetic_sexual_attraction genetic sexual attraction]].) How far their relationship goes before they discover this generally depends on whether the plotline is supposed to be humorous or tragic.

The mentalities of twincest are generally vastly different from BrotherSisterIncest in general. BSI usually caters to ''siscon'', "sister complex", where a male wishes to protect a helpless little girl that looks up to him to the point of idolization -- and her cute cries of "[[BigBrotherComplex oniichan]]!" don't hurt. If it's notable, it's usually an OfficialCouple and the focus of the series. Twincest, however, is almost always composed of YaoiGuys, both of whom are much more mature than the cute little sister, and aimed at {{fangirl}}s; if it's not canon, there will be plenty of girls {{shipping}} it.

An old Japanese myth says that if two star-crossed lovers commit dual suicide, they get reincarnated as twins. This may be one of the factors in the frequency of {{Twincest}} stories in {{anime}}.

Of course, sometimes even {{Twincest}} [[ScrewYourself isn't quite incestuous enough for the writers.]]

Can overlap with a TwinThreesomeFantasy.

----
[[foldercontrol]]

!!Examples

[[folder:Anime & Manga]]
* Picture above: ''CandyBoy'' is entirely about ''[[SchoolgirlLesbians yuri]]'' twincest, in that Yukino does like to tease her sister Kanade quite a bit. There's nothing explicit going on, since Kanade decides to keep a cool outer appearance, although she is obviously enamored with her sister.
* ''{{Black Lagoon}}'''s Hansel and Gretel. [[CreepyTwins Given]] [[AxCrazy their]] [[FreudianExcuse history]], this is possibly the ''[[NightmareFuelUnleaded least]]'' disturbing thing about them.
* A non-canon [[{{shipping}} pairing]] trope popular with fans of the ''{{Digimon}}'' series. Kouji and Kouichi from ''DigimonFrontier'' were SeparatedAtBirth and, to a much lesser extent due to their limited involvement (but still plausible... we're talking one of the most messed-up fandoms in recent memory in regards to who they pair up), Ai and Makoto from ''DigimonTamers'' fall into this. CampGay Rhodo-Knightmon (Crusadermon) makes thinly-veiled {{Twincest}} jokes about Kouji and Kouichi in one memorable episode.
* Shoujo Sect absolutely defines this trope with the Kasagi twins Aki and Nori. [[http://www.mangafox.com/manga/shoujo_sect/v02/c009/23.html Just read their description in the manga itself.]]
* Yoh and Hao in ''ShamanKing'' are twins. In the anime, especially the 4Kids dub, [[strike:Hao]] (I'm sorry, [[{{Americanitis}} Zeke]]) kept saying it was Yoh's destiny to unite with him. A lot of yaoi fangirls love Yoh/Hao.
* Subverted in ''GundamSEED'': Kira and his SeparatedAtBirth twin sister Cagalli meet in the first episode (neither knowing they're related), and when they reunite further in the series, Cagalli comforts the emotionally ragged Kira in a purely platonic way. This is ironically taken as a threat by Flay, Kira's screwed-up girlfriend ([[MindGameShip it's not a healthy relationship]]), despite the fact there's no romantic attraction to it. Further toyed with when Cagalli displays a LuminescentBlush at overhearing Flay admit to her ex-fiancé Ssigh that she and Kira have slept together.
* ''{{Gundam 00}}'' plays with this too. Whether [[DarkMessiah Ribbons]] [[AGodAmI Almark]] and his "sister" [[DarkActionGirl Hilling Care]] qualify as twins is debatable, [[spoiler: both of them being DNA-engineered children with the same sequence]], but Healing seems to show a bit more adoration than is platonic towards Ribbons.
* ''[[DotHack .hack//tasogare no udewa densetsu]]'' hints strongly at incest, or at least lust, between two characters who are twins. This is basically a {{Flanderization}} of subtler jokes in the manga, where it was the sister's completely different-looking and skimpily-dressed computer avatar that set off the whole thing.
** It can't be helped either that the anime altered the storyline near the end where their relationship is implied to be much stronger.
* In ''{{Revolutionary Girl Utena}}'', {{Half Identical Twins}} Miki and Kozue have a bizarre relationship which may involve twincest, particularly in the movie.
* ''OnegaiTwins'' features a boy who is not sure which of the two girls in the story is his long-lost twin sister. They ''both'' fall for him, making one a case of twincest and the other not. Now, if only they knew which...
** And if only the manga and anime were the same on that point...
* ''{{Chobits}}'' has some ''extremely'' un-sibling-like touching between Chi and the "Dark Chi" that appears in her mind. [[spoiler: This proves to be her sister, Freya, whose mind was downloaded into Chi.]]
* In a similar {{CLAMP}} example, see Hinoto and her hallucinatory {{evil twin}} in ''{{X1999}}''.
* On learning that Fai of ''TsubasaReservoirChronicle'' [[spoiler: has a deceased twin brother named Fai (hence why the Fai we know and love is named Fai),]] the fangirls hit the keyboards hard.
** This troper has seen more fanfiction that has Fai making out with his twin than she has fingers to count with.
*** The Acid Tokyo arc's Kamui and Subaru (also known as the "Vampire Twins") actually manage even more HoYay than their counterparts in ''{{X1999}}'' (where they are not related in any way). [[VampiresAreSexGods Vampirism]] (and new twincest possibilities) may have something to do with it.
**** Mercifully, the fanfic authors do ''not'' do this with Syaoran and Sakura and their ''many'' [[ScrewYourself clones]], as that would likely cause the already inscrutable relationship chart (for their fic, anyway) to actively kill those that look at it.
***** It appears you [[http://burnt-sun.livejournal.com/4833.html#cutid1 spoke too soon.]]
* The Hitachiin twins in ''OuranHighSchoolHostClub'' [[GenreSavvy play this up]] for their fangirls for the purposes of their club. They also seem to be ''very'' affectionate toward each other when the fangirls aren't watching, but this, too, could also be a game they play.
** In one episode they are shown to share a bed.
*** Except that bed is actually two beds pushed together.
**** This is highlighted by the fact that one of them (probably Hikaru) emerges with no clothes on except for an elephant face over his crotch that proceeds to spout streamers, in [[DoesThisRemindYouOfAnything what might be some bizarre metaphor.]]
* ''Boku wa Imouto ni Koi o Suru'' ("I'm In Love With My Little Sister")
** Wow... [[ExactlyWhatItSaysOnTheTin everything's in the title]], it seems.
* ''MyselfYourself'' has twins Shuri and Shusuke with a particularly strong relationship in the face of ParentalAbandonment, with a later rumor even claiming a more illicit relationship. [[spoiler:Under threat of separation, they run away together near the end]]. The DistantFinale strongly suggests that the twincest {{subtext}} has become ''canon''.
* The ''{{Kannazuki no Miko}}'' manga ends with [[spoiler:Chikane and Himeko reincarnated as twin sisters]]. [[WallBanger Oh, dear]]. At least they didn't have to go far to find each other again.
** This may be a variation on the Japanese myth mentioned above.
* Many fans pair Vash and Knives from ''{{Trigun}}''. To be fair, it ''is'' strongly implied that Knives has one heck of a brother complex towards Vash. The first big confrontation between Vash and Knives at the very end of the first ''Trigun'' manga really looks like [[spoiler: a metaphorical rape scene complete with grotesquely obvious phallic symbols.]] Which wasn't even the most disturbing thing about this scene in the first place.
* And let's not get started on Rociel / Roshiel's 'ambiguous' attitude towards his twin-sister-Alexiel-reincarnated-into-Setsuna in ''{{Angel Sanctuary}}''. But then again, Rociel isn't a paragon of sanity, and brother-sister incest is one of the main ''themes'' of the manga.
* One of the fanon yaoi pairings in ''{{The Prince of Tennis}}'' involves a set of twins: the Kisarazus, namely Atsushi from Saint Rudolph (short hair, a red bandanna) and Ryou from Rokkaku (long hair, a white hat).
* There are multiple examples of pairing up Netto and [[MegaMan Rockman]] from ''MegaManBattleNetwork''/''MegaManNTWarrior''. It's up to the Gentle Reader to decide which {{squick}}s him or her more -- the game version, where this trope applies in full, or in the anime, where he's just a computer program.
* Amiboshi and Suboshi in ''FushigiYuugi'', though a lot of this is fan speculation. Especially [[spoiler: because Suboshi feeds Amiboshi a mind-erase drug ''[[IntimateHealing through a kiss]]'' in episode 40.]]
** In an author's note in the manga, Yuu Watase claims that she didn't mean for that particular incident to seem so sexual. [[YaoiFangirl Sure]] [[{{Fanservice}} she didn't.]]
* The revelation at the end of ''ChronoCrusade'' that [[spoiler:Chrono and Aion]] are twins hasn't stopped some fans from shipping them. The fact that [[spoiler:Aion]] really does seem to have a brother complex doesn't help dissuade them.
* Zero and his long-lost twin Ichiru in ''VampireKnight''. The 'cest is entirely irrelevant to the plot. It just needed that extra element.
* In an example where the incest ''is'' relevant to the plot, in ''{{Saiyuki}}'' [[spoiler:Hakkai's girlfriend Kanan was actually his SeparatedAtBirth twin sister.]] It's not known when they found out, but it was [[spoiler:Hakkai's]] motive for what he did after [[spoiler:she was given up to the demons by the villagers.]]
* The Hayasaka twins from ''Buso Renkin'', while most likely not involved in ''actual'' twincest, do act a lot like a married couple, and used to recite the traditional wedding vows to each other as a game, as kids.
* In ''{{Full Metal Panic}}: The Second Raid'' the assassins Xia Yu Fan and Xia Yu Lan are twin sisters who take showers together. And hold each other at every available opportunity. [[spoiler:Also Yu Lan sees Yu Fan descending naked from the sky toward her when she dies.]]
* The relationship between Carossa and Melissa in ''GunXSword'' has elements of this, though they are never so pronounced as when the two first appear and Carossa ''licks away Melissa's tears''. Van, watching, cannot help but be a little disturbed.
** Well, they ''are'' basically kids. What was there was creepy, however, particularly Carossa managing to imply "Abusive Relationship" while being and looking all of twelve years old.
* Some ''HigurashiNoNakuKoroNi'' fans like to ship Mion and Shion, despite the fact that both girls have potential canon love interests. The marketing of the series doesn't help.
** If by "potential canon love interests" you mean "are both madly in love with boys in ways that drive the entire plot", that would be correct, yes.
** Ditto for ''LuckyStar'''s Kagami and Tsukasa. There still have been some decent stories involving this couple though.
** Mion and Shion's might have [[http://i332.photobucket.com/albums/m330/Invisiblegrrl5/128.jpg to]] [[http://i535.photobucket.com/albums/ee357/Pichu_Chu/minitokyofemalescanshigurashinon-1.jpg do]] [[http://i91.photobucket.com/albums/k309/Mona_Elric/Posters/1202601632078.jpg with]] [[http://i511.photobucket.com/albums/s355/Sokumei/twin.jpg the]] [[http://i535.photobucket.com/albums/ee357/Pichu_Chu/eviltwin.jpg ever]] [[http://i535.photobucket.com/albums/ee357/Pichu_Chu/p-dvd06.jpg so]] [[http://i257.photobucket.com/albums/hh216/MishaHibiya/MionShion.jpg revealing]], [[http://i535.photobucket.com/albums/ee357/Pichu_Chu/higurashi150.jpg almost]] hentai, twincest official art the animators used to ''promote the first season'', and the manga art. Also, they are a bit touchy touchy.
* ''AyashiNoCeres'' plays this trope quite creepily and mixes it with RapeAsDrama. Also averted, in that the actual twins don't have twincesty feelings for each other; they are, however, possessed by their ancestors, who were husband and wife. SoYeah.
* The [[{{Shipping}} fan pairing]] of [[AxisPowersHetalia USA/Canada]]. The fans they have are few, but ''very'' loyal.
** There are also some Taiwan/Hong Kong and North Italy/South Italy shippers around, but the jury's still out on the subject of these two "couples" being twins or just siblings, though.
* Sadly, ''{{Monster}}'' has some vehement [[MisaimedFandom Johan/Nina shippers]].
* Ranma, from [[{{ptitlegynukzwikxmd}} Ranma 1/2]], whenever his female and male side become distinct in mind and body. The clone of his female self and the clone of his male self even hook up together, perhaps even creating a fair amount of {{squick}}, IfYouKnowWhatIMean. Since they are of different body and mind but have the same genetic code, this would be a extreme case of both twincest and [[{{screw yourself}} narcissism]].
** Not entirely correct. When (anime-only) Happosai created a phantasmal copy of Ranma's female side, it was a fairly evil shadow that mystically ensnared (i.e. hypnotized) the real Ranma to drain his LifeEnergy. When (manga-only) a haunted mirror created an actual clone of female Ranma, said clone kept some of Ranma's skills and memories, but the real Ranma was supremely put off by her advances. Although he flattered her when ''his'' ego was compromised, he wanted absolutely nothing to do with her (except sealing her back in the mirror, that is.) When the male clone came out and the two copies paired up, it was more due to the haunted mirror's GhostlyGoals (to hook up with a cute girl/boyfriend) than this trope or narcissism.
* Suiseiseki and Souseiseki, aka the [[FanNickname Boatlight Twins]], from ''RozenMaiden'' get th is kind of treatment a lot through fan shipping. To be fair, they are an official pairing in the series itself, so it works out pretty well overall anyway.
* Basically the entire point of ''KissxSis'' is a pair of fraternal twins trying to get with their brother in this manner (don't worry though, they're NotBloodSiblings).
[[/folder]]

[[folder:Comics]]
* In the [[UltimateMarvel Ultimate Marvel Universe]], there were hints about Quicksilver and Scarlet Witch going down this road from the beginning, until [[spoiler:it was confirmed outright in a recent issue of ''TheUltimates'', immediately before her death.]]
** This Troper thinks that the twin's relationship was iffy ''long before'' Ultimates...
* Marvel Comics' Fenris twins (Andrea and Andreas Von Strucker) play with this idea (and likely, each other!) fairly frequently. Shudder.
** It gets worse. [[spoiler: Andrea has since died, and since their energy blast powers relied on them touching to function, her brother had her skin made into leather and [[DoesThisRemindYouOfAnything wrapped his sword hilt with it]]. On top of that, he is nothing short of fanatically obsessed with finding a way to resurrect her.]] The whole thing is portrayed just as creepily as it sounds, with even other characters around him being {{squick}}ed by it.
*** Their Ultimate versions were pretty much the same, save for the bit in spoilers up there.
* It was heavily implied in a few issues of ''Infinity, Inc.'' that Obsidian had a crush on his long-lost twin sister Jade. She was blissfully oblivious.
* TopTen's SpinOff miniseries ''{{Smax}}'' has [[spoiler: Smax and his sister Rexa admitting to this]], although in the world they came from it wasn't the taboo issue it was in his adopted world.
[[/folder]]

[[folder:Fan Works]]
* ''Harry Potter'' offers the Weasley twins as a prime example of this trope in fanfiction.
* The twin sons of Elrond, Elladan and Elrohir and (to a much smaller extent) Elrond and his twin brother Elros are frequently paired in ''Lord of the Rings'' fanfiction.
* ''EdgarAndEllen'' fandom has quite a few of these. This troper [[DidntSeeThatComing Did See That Coming.]]
* {{Vocaloid}} fanfictions are full of these, featuring Kagamine Len x Kagamine Rin. Not that the music videos (also made by fans, of course) would help much...
[[/folder]]

[[folder:Films]]
* Narrowly averted (at least according to {{Fanon}}) in ''StarWars'': the viewers (and the characters themselves) are initially led to expect a love triangle between Luke, Leia and Han, but then it is revealed in ''Return of the Jedi'' that Luke and Leia are actually twins.
** However, the novel ''Splinter of the Mind's Eye'' was written and takes place before their relationship was revealed and so features romantic scenes with the two.
** When this troper saw the re-release of ''The Empire Strikes Back'' in the theaters, the scene where Leia kisses Luke (to make Han jealous, and rather passionately) invoked horrified groans from the audience, 'cause we ''knew''!
* David Cronenberg's 1988 film ''Dead Ringers'' features some creepily sexual scenes between Jeremy Irons ''and'' Jeremy Irons as twin gynecologists Beverly and Elliot.
** Based on the novel ''Twins'', later re-released as ''Dead Ringers''.
* {{Creepy Twins}} Wendell and Darlene from the horror film ''The Hamiltons''.
* Pretty much the basic plot of ''The House of Yes'', with Parker Posey.
* Julie Taymore's film version of ''Titus Andronicus'' portrays Chiram and Demetrius this way. They're just as touchy-feely with their mom, too. It's okay, though, because Anthony Hopkins puts them in a pie.
* ''Hellboy II: The Golden Army''. Okay, the twincest doesn't actually ''happen'', but boy, does Prince {{Badass}} {{Bishonen}} Faerie want it to.
* Ryan and Sharpay Evans from ''HighSchoolMusical'' have a suspiciously close relationship, what with singing love songs to each other and playing romantic leads opposite each other. Plus there's that video of "I Can't Take My Eyes Off of You", a song in which Troy, Gabriella, Ryan, and Sharpay all sing -- Troy and Gabriella (established couple) sing to each other and Ryan and Sharpay... also sing to each other. Sample lyrics: "I can't take my eyes off of you/ I know you feel the same way too" and "You never really know what you might find/Now all I see is you and I/ You're everything I never knew that I've been looking for."
** That could be one of the reasons that song was left out of the film, but I think the song was originally meant just for Troy and Gabriella, like it is in the play version. And, in that video, it was the actors singing. (Except Zac Efron...)
** "If Sharpay could figure out a way to play Romeo and Juliet at the same time, her brother would be out of a job."
** The playing romantic leads against one another is actually not all that uncommon in Real Life theatre companies -- these were often family based, and if the principle players were brother and sister, well...There was one actress in Regency England who was happily married and, her husband not being an actor, actually ''refused'' to play romantic leads against anyone ''except'' her brother.
* In ''EuroTrip'', Jenny and Jamie get trashed on absinthe and make out. They are appropriately horrified the next morning.
*How can anyone omit "The Dreamers"? That movie's teeming with this trope!
** It wasn't obvious (to this troper at least) that the siblings were twins. Maybe it belongs under BrotherSisterIncest?
[[/folder]]

[[folder:Literature]]
* Cersei and Jaime Lannister in ''{{A Song of Ice and Fire}}''. [[spoiler:Jaime is revealed to be true father of Queen Cersei's children, thus making them false heirs to the throne. This eventually is one of the main causes of the following civil war.]]
** Goes from pretty nasty to very squicky when it's revealed that they were in love with each other even as little children. Cersei even implies that the bond went back to ''birth'', seeing as the two shared a womb, something that squicks the everloving fuck out of [[spoiler: Ned Stark]].
*** [[{{YMMV}} Not everyone is squicked by that...]]
* Implied in EdgarAllanPoe's Gothic horror story ''The Fall of the House of Usher''.
* RobertHeinlein's recurring hero Lazarus Long has two OppositeSexClone copies of himself, which seem very, ''very'' twincesty, on top of the hero sleeping with them both in the first place.
** Not sure if this counts per se, but in ''"... All You Zombies"'' [[spoiler:the main character is both his own father and mother, ''and'' the bartender who gets the "two" of them together]].
* There's a rather bizarre example in ''Fifth Quarter'' by Tanya Huff. The soul of Bannon is forced to share the body of his twin sister Vree when another man steals his body. Vree goes after her brother's body, and when they find it, they devise a plan that Vree will distract him by seducing him, and Bannon will "push" the interloper out his body. Partway through, Vree realizes that Bannon is [[ScrewYourself more interested in seducing himself]] than in getting his body back, and calls it off.
* Twins Charles and Camilla from Donna Tartt's ''The Secret History'' are revealed to be sleeping together towards the end of the book, although it is hinted at earlier in the book.
* Twins Estha and Rahel in Arundhati Roy's ''God of Small Things''.
* Shelley and Kipling in Judith Hawke's ''Heart of a Witch'' get into a ''very'' complicated relationship that was hinted at from the beginning with Shelley's possessiveness of her brother. Even more weirdly, this eventually turns into a ''threesome'' with [[spoiler:Snow, the leader of the coven that they join]].
* In P.C. Hodgell's ChroniclesOfTheKencyrath series, Highborn Kencyr families used to practice sibling and cousin marriage extensively in order to breed Shanir (individuals manifesting powers of their triune God). Twin marriage was especially valuable for this, since it reinforced traits so strongly in offspring. Since a married pair of twins betrayed their people to the BigBad and killed off two-thirds of them a few thousand years ago, it's fallen somewhat out of favor, but families that stick to the Old Ways still only breed with others in the extended family. [[spoiler:The heroine and her twin brother are, by book 4 (''To Ride a Rathorn''), having very powerful erotic dreams together and some highly sexually charged meetings, and WordOfGod says that they have SingleTargetSexuality and will end up together (although not for a while; they have a lot of angst to get past first, especially brother).]] It's notable that some of the results of constant incest seem to be prevalent in the Highborn; they're dying out, fertility is down, childbed mortality is high, and some families are getting rather strange indeed.
* ''The Thirteenth Tale'' has the twins Adeline and Emmeline. It's more of a incredibly close bond between twins, but with damn powerful implications.
* ''Children of {{Dune}}'' has some pretty heavy overtones about Leto II and Ghanima's relationship at times.
** From Leto II's own mouth: "Let us pass puberty living in the same house, and all your taboos will be as a red rag waved in the face of a Sandworm." Perhaps mercifully, he [[spoiler:undergoes transformation into a sandworm-like creature prior to puberty, thus removing this pairing from consideration.]]
*** ...Of course, that doesn't stop him from marrying her later. But both of them are in complete agreement about the fact that there will be no weirdo hanky-panky going on, and that all her children will be bastards sired by a [[FeudingFamilies Corrino]] survivor, specifically the [[spoiler:direct descendant of the emperor Leto's father deposed]]. (Though ''they're'' in love anyway, so, [[EarnYourHappyEnding good for them]].)
* ''Stalking Tender Prey'' by Storm Constantine has, within the first few chapters, a pair of twins who, because they are [[spoiler: hybrids of human, and a very oversexualised variation on the Nephilim, and the only two in the area, and therefore can only express themselves to each other]] get into twincest an awful lot. They're also HalfIdenticalTwins though this is not out of prudishness on the authors part, as one of them later turns out to be massively bisexual, and, lets be fair, most of the main characters do bedhop with most of the other main characters. In fact the main antagonist, as [[spoiler: THE fallen angel, effectively satan]] pretty much gets to bonk 98% of the main characters. Repeatedly.
* [[http://www.strangesisters.com/a-z/images/crap_shoot.php?start=792&data=strangesisters.list&photo=xtwincest.jpg This]] [[ExactlyWhatItSaysOnTheTin aptly titled]] (and {{NSFW}}) pulp novel.
* It's really, ''really'' difficult to read the opening [[{{Doorstopper}} few hundred pages]] of ''[[TheBelgariad Polgara the Sorceress]]'' without reading some seriously odd romantic undertones into the relationship between non-identical twin sisters Beldaran and Polgara: not only does Beldaran have her sister completely wrapped around her adorably girly little finger, but they're apparently sharing a bed well into adolescence at least on the occasions when Polgara hasn't decided to run away and live in a tree, and Pol's ''explicitly'' possessive anger when Beldaran gets engaged would be a little freakish in its intensity even coming from an actual romantic rival.
* In GeneWolfe's ''{{Book of the New Sun}}'', twins Agia and Agilus are found to have an incestuous relationship when Severian [[spoiler: enters Agilus' cell the day before his execution, only to find the brother and sister nude and huddled together.]] Agilus admits, "Everything you suspect is true," the implication being incest.
[[/folder]]

[[folder:Live Action TV]]
* In the final episode of ''ArrestedDevelopment'', [[spoiler:Michael's twin sister Lindsay admits that she's attracted to him]]. However, this is only after the revelation that [[spoiler:Lindsay is [[NotBloodSiblings adopted]]]].
* It's impossible to watch Maya and Alejandro Herrera in ''Series/{{Heroes}}'' without thinking about it. [[spoiler:After all, Maya killed everyone but Alejandro and herself during her twin brother's wedding after she learnt that [[YourCheatingHeart his bride to be was cheating on him]]...]]
* ''{{House}}'' points out that two identical female twins who are both fighting to join his team are "distracting to every man and lesbian in the room".
* There was a pair of fraternal male twins that the main characters used to go to school with on ''ItsAlwaysSunnyInPhiladelphia'' that were sexually involved. Turns out the entire [=McPoyle=] family is one large, ingrown incestual orgy. It's just about the creepiest thing this troper has seen on television.
* Jack from ''WillAndGrace'' has, as his life's ambition, to one day meet and have sex with a pair of male identical twins. Will once actually invited over a pair of gay identical athletic twins just to make Jack jealous.
* Katie and Emily Fitch from ''{{Skins}}''. Moreso Katie than Emily; she states that Emily is "hers" and Naomi (who is romantically involved with Emily) could never love Emily as much she does. It doesn't help that at one point during the end of the twins' episode in series three, when Emily is confronting Katie, someone in the crowd yells out that Emily should kiss her.
* LampShaded in ''Buffy the Vampire Slayer'', when Xander is split into two Xanders by a demon(who was aiming for Buffy instead). Anya wonders out loud if the spell to recombine them has to be done right away, saying that if they held off, "I could take the boys home, and we could all have sex together."
* In an episode of ''{{Medium}}'', some characters came across a porno that featured this.
* ''HowIMetYourMother'' had this in the 2nd episode of season 3 between Robin and "Vacation Robin". It was AllADream.
* Definitely played with by John and Edward in ''XFactor'', such as their routine to "Oops I Did It Again", which involved the talky bit ("but I thought the old lady threw it into the sea at the end of the movie").
[[/folder]]

[[folder:Music]]
* This troper finds this implied when The Veronicas, a band consisting of twin sisters sing "All About Us", a song by T.a.T.u., apparently SchoolgirlLesbians.
** And at least one of them is [[http://www.news.com.au/entertainment/story/0,26278,24120587-7484,00.html rumoured to be a lesbian]], which would presumably fuel such speculation.
* Similarly, when RyanDan (another twin band, of the male variety) sing mushy romantic duets to one another.
** Well, at least one can sing soprano very well.
* More willfully-interpreted HoYay: [[http://i39.tinypic.com/21l51yv.gif Bill and Tom Kaulitz]], of German band Tokio Hotel.(New .gif for your pleasure! More lap-bouncing, less arm-tugging)
** [[http://www.fiction.tokiohotelfiction.com/browse.php?type=categories&catid=1 So]]...[[http://community.livejournal.com/tokiohotelslash/tag/twincest much]]...[[http://morethantwins.com/fanfic/fanfic.php fanfiction]]... It's staggering how...[[http://morethantwins.com/fanart/nightingale/twinart.php dedicated]] these fangirls are.
** At least once when performing live Bill has ''dropped to his knees in front of Tom'', while singing a song supposedly about Tom and a groupie. More specifically, he sang "Ich will mit keiner ausser Dir." Which roughly, in context, translates to "I don't want to do it with anyone but you." He ALWAYS sings that part to Tom.
** I thought the band was Nightmare Fuel. But this... is BeyondTheImpossible, and very much NightmareFuelUnleaded [[RecycledInSPACE cranked up to 11.]] Good Lord - WTF ?
*** What -- the fanfiction, the kneeling, or the fact that Bill is bouncing in Tom's lap (and pulling Tom's arm towards his crotch) in the .gif?
**** For this troper at least, it's the combination of all three.
** Bill has also commented on these stories saying: [[http://www.imeem.com/groups/C54-ty4W/blogs/2007/08/18/0o4yGsx8/bill-kaulitz-answers-24-questions-through-chat "Everybody can have his fantasies…though they are sometimes really absurd…but they do exist for that…"]] Hmm-HMMM.
** And here this troper was beginning to think nothing could top Waycest. She has been wronged at the expense of receiving more NightmareFuel.
* Tegan and Sara are attractive identical twin sisters who also happen to be lesbians. This troper's lesbian friends like this concept very much.
[[/folder]]

[[folder:Music Videos]]
* This seems to be the gist of the relationship between the Kagamine twins of {{Vocaloid}}, at least among the fandom.
** The fact that a lot of people shipping either of them with others hate the Rin x Len pairing on incest grounds is a focal point of the ShipToShipCombat in the Vocaloid community, despite none of them having any personalities or character traits other than Rin and Len being siblings due to Crypton being SureWhyNot with their fan interpretation.
[[/folder]]

[[folder:Porn]]
* While incest tropes in general are rarer in visual pornography than one would expect, this one is practically non-existent due to the fact that the handful of twins who work in porn -- like any real twins -- generally would never do something like that.
** There have been a few noteworthy exceptions. The earliest was a pair of alleged fraternal twin sisters Brooke and Taylor Young, who were quite willing to have sex with each other in a number of features, most notably ''Teenage Twins''.
** The other more recent exception occurred in the last video that the Love Twins, Lyndsey and Lacey Love, made for Vivid Video, which involved them involved in a group sex scene that culminated in the twins [[spoiler: mounted on either side of a double headed dildo, ''not'' thrusting it with their own hips but having it pulled back and forth by Brianna Banks.]] Other than that, and even after they left Vivid, the Love Twins generally only engaged in [[TwinThreesomeFantasy Twin Threesome Fantasy]] type scenes.
** There are at least three male/male examples of this.
** The Milton Twins Cali and Cherish have avoided this very carefully, but have at least one video (for FuckingMachines) where they use all sorts of appliances on each other. [[YourMileageMayVary If only they were a bit hotter though]]...
** And lets not forget 24y/o Japanese twin adult film stars turned-wannabe-idols Airi and Meiri, who did scenes together and with each other. Kinda of ruined by the fact that they look like they're all of about fourteen years old. [[YourMileageMayVary Then again...]]
[[/folder]]

[[folder:Print Media]]
* Expect this in any pictorial featuring twins in the less classy porn magazines.
* In 2003, Shane and Sia Barbi sued ''Hustler'' for unauthorized use of photos showing "intimate sexual acts between the twin sisters".
[[/folder]]

[[folder:Theatre]]
* This trope (along with a helping of CreepyTwins) is the premise of Marina Carr's play ''Portia Coughlan''. Portia is haunted by her twin brother Gabriel, who drowned himself as a teenager; the fact that she's still obsessed with him fifteen years later (and that Gabriel is referred to as "unnatural") hints heavily towards this, so it's no surprise when she reveals that their relationship was sexual. It's a bit more surprising when [[spoiler: her aunt reveals that Portia's parents, too, are half-brother and sister, though neither of them know it.]]
[[/folder]]

[[folder:Video Games]]
* Continuing FireEmblem's proud tradition of BrotherSisterIncest, ''The Sacred Stones'' gives us the twin siblings Eirika and Ephraim, whose in-game supports all but outright spell it out.
** It's worth noting that the Japanese version allows them to marry.
* ''ResidentEvil: Code Veronica'' implies that Alfred's devotion to Alexia goes some way beyond mere intense admiration.
** The novelization pretty much states it outright.
* ''[[DevilMayCry Devil May freakin' Cry.]]'' It doesn't help that Dante and Vergil are ridiculously pretty and there's a lack of female characters (that don't look like their mom.)
* ''MetalGearSolid'', being chock full of HoYay moments, certainly didn't shy from playing with this trope. In the first game, Liquid Snake strips Solid Snake's shirt off while the latter was unconscious, and there was his desperate need to prove that he was the [[IfYouKnowWhatIMean dominant]] brother. Naturally, it's kicked up to overdrive in the remake. It also certainly didn't help that Liquid was a LargeHam and his voice actor, Cam Clarke, seemed to have an uncanny ability to make the word "brother" sound very erotically incestuous.
** Liquid does blatantly say that part of his motivation is that, 'in Nature, family members don't mate with each other, but they help each other to survive'. [[YouFailBiologyForever Bad biology aside]], it's pretty easy to overthink how that would justify him killing his brother instead of 'helping him to survive'
* ''FatalFrame II: Crimson Butterfly'', with their whole "becoming one with your other twin". One of the key plot elements of the game is the fact that [[spoiler:the village use to perform rituals in which the older twin would strangle the younger one, who would then become one spiritually with the older twin]] and then they'd get to be togeetheeer foreeveeer. This whole "I want to be with only YOU, -insert other twin's name here-!!" thing happens with prettymuch all of the Twin Shrine Maidens depicted in the game, including but not restricted to Azumi and Akane Kiryu, the protagonist Mio and her sister Mayu, and the antagonist Sae with her sister Yae. Sae seems to be the one with the most weirded-out obssession with her sister, since [[spoiler:she seems to all along have fantasized about the day that she'd get to be strangled by Yae]] by the end of the game you find a crystal left by her that is pretty much along the lines of [[spoiler:"Oh Yae, kill me, KIIILLL MEE" like she's getting turned on by the idea.]]
** Not to mention in the promotional comercials, Mio and Mayu are shown in a number of amusingly suggestive poses together. [[spoiler:The strangling pose Mio puts hersel fin above Mayu at the end of the game in Normal mode is also very suggestive.]]
*** Aaaaand some official art has them sitting together or swiming together in bikinis. [[http://www.cameraslens.com/gallery/albums/userpics/10003/2223.jpg Very...]] [[http://www.cameraslens.com/gallery/albums/userpics/10003/poster.jpg very]] [[http://www.cameraslens.com/gallery/albums/userpics/10003/2425.jpg closely.]]
* In the PSX rpg ''Dragon Valor'', the grandson and granddaughter of Clovis, the game's first protagonist, are fraternal twins who are the "most important thing" to each other. It is revealed in the final scene that they are forced to keep their love a secret most of the time as they can only freely express their mutual affection in places where "nobody knows that they're the prince and princess" (i.e. brother and sister).
* In ''{{Xenosaga}}'', Albedo is revealed to have been the conjoined twin of [[spoiler: Junior]]. And let's just say that Albedo... was [[StalkerWithACrush really obsessed with him]], to the point where the thought of being unable to stay with him forever drove him [[AxCrazy mad]].
* In ''[[KingsQuest King's Quest III]]'', after [[strike: Gwydion]] Alexander frees his twin sister Rosella and talks to her, he seems attracted to her in a not-so-platonic way. Of course, they were also SeparatedAtBirth.
* In ''{{Odin Sphere}}'', [[spoiler: Ingway seems to love Velvet in a more-than-brotherly way.]]
* Weiss and Nero from ''FinalFantasyVII: Dirge of Cerberus''. Oh. ''God''.
[[/folder]]

[[folder:Web Original]]
* Whilst nothing explicit has happened (''Yet?''), ''{{Survival of the Fittest}}'' V3 characters Lenny and Elizabeth have a whole lot of {{Subtext}} in their relationship, prompting a lot of 'speculation' amongst members of the board. It isn't clear precisely what relationship the pair have, but it is implied it goes further than being simply siblings.
** Recently the handler more-or-less addressed this issue, quoting a {{Fanfic}} in this first half of one of his posts. This editor was immensely relieved to discover it was a trick.
[[/folder]]

[[folder:Western Animation]]
* ''Robot Chicken'' has a long running gag portraying the Bush twins, Barb and Jenna, as hard-partying ''Girls Gone Wild'' types, often ending with the two of them making out.
** During the ''StarWars'' special, there was the inevitable skit involving Luke and Leia in bed.
[[/folder]]

[[folder:Real Life]]
* A pair of [[SeparatedAtBirth separated at birth]] twins in the UK had their marriage annulled when they discovered their relation. [[http://www.telegraph.co.uk/news/uknews/1575267/Marriage-of-twins-fuels-adoption-row.html]]
* HoYay example: Kyle and Lane Carlson, twin male models. This editor would like to go no further. [[TwinThreesomeFantasy Your milage may definitely vary]], though.
* This troper regularly posts on an RPG message board with a thread on the creepiest person you've ever gamed with. Once, a mod dropped a mention of a "twincest" story. This led to hundreds of pages of half-joking cries of "TWINCEST!?!" as the posters demanded to know more.
* [[RedneckRocker This Troper]] once included a brother-sister twin duo in a MutantsAndMasterminds setting, who seemed a [[IfYouKnowWhatIMean little too close]] with one another. [[spoiler:It's eventually revealed that they're not really into that sort of perversion; it's all just an act to freak people out.]]
[[/folder]]

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