Incest

Incest is sexual activity between two persons related by close kinship. In some societies this is enforced with the legal or social prohibition to marry. Although not universal, incest constitutes a cultural taboo in most current nations and many past societies., with legal penalties in some places. In some societies, like Ancient Egypt or Achaemenid Persia, brother–sister, father–daughter and mother–son relations were practiced.

Which family members constitute those covered by the incest prohibition is determined by the society in which the persons live. Some societies consider it to include only those related by birth or those who live in the same household; other societies further include those related by adoption, marriage, or clan.

The term incest can include sexual activity between family members of any gender and can include family members of any age. When one of the family members involved is a minor, incestuous activity has also been called intrafamilial child sexual abuse.