Incest between twins or "twincest" is a subclass of

sibling incest Siblings play a unique role in one another's lives that simulates the companionship of parents as well as the influence and assistance of friends. Because siblings often grow up in the same household, they have a large amount of exposure to one ano ...

and includes both heterosexual and

homosexual Homosexuality is romantic attraction, sexual attraction, or sexual behavior between members of the same sex or gender. As a sexual orientation, homosexuality is "an enduring pattern of emotional, romantic, and/or sexual attractions" to peop ...

relationships. 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 The House of Lords, also known as the House of Peers, is the Bicameralism, upper house of the Parliament of the United Kingdom. Membership is by Life peer, appointment, Hereditary peer, heredity or Lords Spiritual, official function. Like the ...

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. 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". His study drew on Edvard Westermarck's

hypothesis A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous obse ...

that sexual desire is generally absent in relationships between members of a

nuclear family A nuclear family, elementary family, cereal-packet family or conjugal family is a family group consisting of parents and their children (one or more), typically living in one home residence. It is in contrast to a single-parent family, the larger ...

In Asian culture

In traditional

Bali Bali () is a province of Indonesia and the westernmost of the Lesser Sunda Islands. East of Java and west of Lombok, the province includes the island of Bali and a few smaller neighbouring islands, notably Nusa Penida, Nusa Lembongan, and Nu ...

nese culture, it was common for a set of

twin Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...

s of the opposite sex to marry each other, since it was assumed that they had had sex in utero. The standard anthropological explanation of this custom is based in explications of the conflicts between

descent Descent may refer to: As a noun Genealogy and inheritance * Common descent, concept in evolutionary biology * Kinship, one of the major concepts of cultural anthropology **Pedigree chart or family tree **Ancestry **Lineal descendant **Heritage (d ...

and affinity in Balinese society. Incest was commonplace in

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...

creation myth A creation myth (or cosmogonic myth) is a symbolic narrative of how the world began and how people first came to inhabit it., "Creation myths are symbolic stories describing how the universe and its inhabitants came to be. Creation myths develop ...

s which prominently featured twin or sibling couples. In these stories, the brother usually wooed and wed his sister, who bore his child or children, but on discovering that they are siblings, they are often (but not always) forced to part.

In European culture

Twin incest is a prominent feature in ancient Germanic mythology, and its modern manifestations, such as the relationship between Siegmund and Sieglinde in

Richard Wagner Wilhelm Richard Wagner ( ; ; 22 May 181313 February 1883) was a German composer, theatre director, polemicist, and conductor who is chiefly known for his operas (or, as some of his mature works were later known, "music dramas"). Unlike most op ...

's '' Die Walküre'', and a feature in some

Greek mythology A major branch of classical mythology, Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the Cosmogony, origin and Cosmology#Metaphysical co ...

, such as the story of Byblis and Kaunos. There are strong parallels between the Germanic portrayals of twin incest and those of the Balinese

Ramayana The ''Rāmāyana'' (; sa, रामायणम्, ) is a Sanskrit literature, Sanskrit Indian epic poetry, epic composed over a period of nearly a millennium, with scholars' estimates for the earliest stage of the text ranging from the 8th ...

, and some scholars have speculated an early

Indo-European The Indo-European languages are a language family native to the overwhelming majority of Europe, the Iranian plateau, and the northern Indian subcontinent. Some European languages of this family, English, French, Portuguese, Russian, Dutch ...

link. The theme also appears in

English literature English literature is literature written in the English language from United Kingdom, its crown dependencies, the Republic of Ireland, the United States, and the countries of the former British Empire. ''The Encyclopaedia Britannica'' defines E ...

, such as the incest between the twins Polydore and Urania in

Delarivier Manley Delarivier "Delia" Manley (1663 or c. 1670 – 24 July 1724) was an English author, playwright, and political pamphleteer. Manley is sometimes referred to, with Aphra Behn and Eliza Haywood, as one of "the fair triumvirate of wit", which is a la ...

's ''The New Atalantis''. The fantasy fiction series ''

A Song of Ice and Fire ''A Song of Ice and Fire'' is a series of epic fantasy novels by the American novelist and screenwriter George R. R. Martin. He began the first volume of the series, ''A Game of Thrones'', in 1991, and it was published in 1996. Martin, who init ...

'' describes a secret relationship between

Jaime Jaime is a common Spanish and Portuguese male given name for Jacob (name), James (name), Jamie, or Jacques. In Occitania Jacobus became ''Jacome'' and later ''Jacme''. In east Spain, ''Jacme'' became ''Jaime'', in Aragon it became ''Chaime'', and i ...

and Cersei Lannister, who are

fraternal twins Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...

. Within the setting of the books, various historical characters from House Targaryen were married to their siblings.

References

{{Incest Incest Twin