List of coupled siblings

This article lists well-known individuals who had romantic or marital ties with their sibling(s) at any point in history. It does not include coupled siblings in works of fiction, although those from mythology and religion are included.

There are many terms used to describe a romantic bond between siblings, including formal nomenclature such as adelphogamy, specific hyponyms such twincest, or slang terms like sibcest. In a heterosexual context, a female partner in such a relationship may be referred as a sister-wife. A similar incestuous arrangement which is non-monogamous can be referred as sister-swapping or brother-swapping, although this should not be confused with berdel, which describes the situation in which families exchange brides or bridegrooms.

Earliest sibling marriages can be traced back to creation myths of early civilizations in Egypt and West Asia. Partly impacted by their creation myths, royal brother-sister marriages were historically practiced among royalty in Ancient Egypt, particularly the Eighteenth and Nineteenth Dynasties, and Ptolemaic Egypt. Sibling marriages were also found in the pre-Columbian Inca Empire of Peru, in pre-colonial Hawaiʻi, sporadically throughout Eurasia, particularly the Achaemenid Empire and the Hellenistic reigns, and in various other places.

While cousin marriage is legal in most countries today (less often with regard to first cousins), and avunculate marriage is legal in several, sexual relations between siblings are considered impermissibly incestuous almost universally. Sibling marriage is legally prohibited in most countries worldwide,^{[citation needed]} with a partial exception being Sweden, where marriages between half-siblings are legally permitted.

Innate sexual aversion between siblings forms due to close association in childhood, in what is known as the Westermarck effect. Children who grow up together do not normally develop sexual attraction, even if they are unrelated, and conversely, siblings who were separated at a young age may develop sexual attraction. Thus, many cases of sibling incest, including accidental incest, concern siblings who were separated at birth or at a very young age.^{[citation needed]}