Incest between twins

Incest between twins is a subclass of sibling incest and includes both heterosexual and homosexual relationships. In traditional Balinese culture, for example, a set of twins of the opposite sex were forced to marry each other, since it was assumed that they had had sex in utero. In traditional Mohave culture, opposite-sex twins were thought to have been married in heaven.

In a review of the scholarly literatures on twin homosexuality and twin incest, Ray Bixler concludes that "most same sex homosexual twins, if reared with their co-twins, do not attempt or even want to seduce them in adulthood". His study draws on Edvard Westermarck's hypothesis that sexual desire is generally absent in relationships between members of a nuclear family.

One case of incest between twins, in which a pair of twins who were adopted by separate families as babies later married without knowing they were brother and sister, was mentioned in a House of Lords debate on the Human Fertility and Embryology Bill in January 2008. According to the charity Adults Affected by Adoption, there had been other cases of this sort that had involved siblings. The story was widely publicised in the British press, although its truthfulness was called into question.

Popular culture

Main article: Incest in popular culture

Other depictions of or references to it can be found in fanfiction (where it is usually referred to as "twincest" [a term used by Noah Dillon]), traditional folklore, erotic and pornographic magazines and videos, advertising, and even mainstream films. In the latter two cases, incestuous relationships between twins are usually only implied and almost always used for a shock effect.

• In Richard Wagner's The Ring of the Nibelung, twins Siegmund and Sieglinde commit incest at the end of Act 1 of Die Walküre. The offspring of this union is Siegfried, the hero of the next operas in the Ring cycle, Siegfried and Götterdämmerung.
• In Melvin Burgess's novel Bloodtide, which, like "Die Walküre", is based upon the Volsunga Saga, the Volson twins Siggy and Signy share an incestuous sexual encounter which leaves Signy pregnant. However, Siggy is unaware that it is his sister, since she is in the guise of another character, Cherry.
• Incest between twins figures prominently in Thomas Mann's 1905 novella Wälsungenblut (The Blood of the Walsungs).
• The House of Yes features Parker Posey and Josh Hamilton as fraternal twins Jacqueline and Marty, whose incestuous relationship is complicated by Marty's engagement to Lesly (Tori Spelling).
• In the film Cruel Intentions 2, identical twins Alicia and Annie Sorell kiss during a nude shower scene with actor Robin Dunne.
• In the book "De uanstændige" by the Danish writer Leif Panduro, the protagonist twin couple has an incestuous relationship with each other.
• In Bertolucci's movie The Dreamers (film), twins Isabelle and Theo have a very close, incestuous relationship, although it is not revealed if they engaged in sexual intercourse. They are not shown to do anything directly passionate, but bathe and sleep together in the nude.
• Trey Parker, the creator of South Park, recorded a song in 1985 on a cassette tape Immature: A Collection of Love Ballads for the '80s titled Twin Brothers In Love.
• In George R. R. Martin's series of novels, A Song of Ice and Fire, an incestuous relationship between twins Cersei and Jaime Lannister is a major plot point and is described in explicit detail throughout the series.
• In Anne Rice's Blackwood Farm, the Twins Tarquinn (Quinn) and "Goblin" had a sexual relationship. His spirit would try to do sexual acts on his twin. While Quinn was not in love with his brother, it is enough for some to think that Goblin does think of Quinn romantically.
• In another one of Anne Rice's books, The Witching Hour there was a set of twins who had a child together.
• In the movie EuroTrip, twins Jamie and Jenny, kiss each other at a night club after drinking absinthe, although this is entirely due to their inebriation, and both are horrified and humiliated upon realizing who their partner is.
• In Marvel Comics Andreas and Andrea Strucker the twin children of villain Baron Strucker were lovers prior to Andrea's murder (a fact Baron Zemo, a family acquaintance, confirms by saying they had run out of sexual positions to try). The bizarre undertone of the incestuous relationship between the twins has become a minor but recurring plot element in the Thunderbolts comic series of which Andreas is a main character.
• In Ultimate Marvel Scarlet Witch and Quicksilver the twin children of Magneto have an incestuous relationship.
• In the book The God of Small Things, fraternal twins, Esthappen and his sister Rahel have sex.