Incest was commonplace in Southeast Asian creation myths which prominently featured twin or sibling couples. The standard anthropological explanation of this custom is based in explications of the conflicts between descent and affinity in Balinese society. In traditional Balinese culture, it was common for a set of twins of the opposite sex to marry each other, since it was assumed that they had had sex in utero. His study drew on Edvard Westermarck's hypothesis that sexual desire is generally absent in relationships between members of a nuclear family. In a 1983 review of the scholarly literature on twin homosexuality and twin incest, Ray Bixler concluded that "most same-sex homosexual twins, if reared with their co-twins, do not attempt or even want to seduce them in adulthood". The story was widely publicised in the British press, although its truthfulness was called into question. According to the charity Adults Affected by Adoption, there had been other cases of this sort that had involved siblings. One supposed case of incest between twins, in which twins who were adopted by separate families as infants 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.
Incest between twins or " twincest" is a subclass of sibling incest and includes both heterosexual and homosexual relationships. For other uses, see Twincest (disambiguation).