Incest:
Incest is sexual activity between family members and also, close relatives. This typically includes sexual activity between people in a consanguineous relationship (blood relations), and sometimes those related by affinity, such as members of the same household, step relatives, those related by adoption or marriage, or members of the same clan or lineage. The incest taboo is and has been one of the most widespread of all cultural taboos, both in present and in many past societies. Most modern societies have laws regarding incest or social restrictions on closely consanguineous marriages.
In societies where it is illegal, some as a victimless crime sees consensual adult incest. Some cultures extend the incest taboo to relatives with no consanguinity such as milk-siblings, stepsiblings and adoptive siblings. Third-degree relatives (such as half-aunt, half-nephew, first cousin) share 12.5% genes, and sexual relations between them is viewed differently in various cultures, from being discouraged to being socially acceptable.
In some societies, such as those of Ancient Egypt and others, brother–sister, father–daughter, and mother–son, cousin-cousin, aunt-nephew, uncle-niece, and other combinations of relations were practiced among royalty as a means of perpetuating the royal lineage. Some writers have described the marriage of Cain to his sister Awan as the first instance of incest. Some societies, such as the Balinese and some Inuit tribes have different views about what constitutes illegal and immoral incest. However, parent-child and sibling-sibling unions are almost universally forbidden.
The justification often given for the incest taboo is the impact of inbreeding on the children of incestuous sex. Children whose biological parents have a close genetic relationship have a greatly increased risk of congenital disorders, death and disability at least in part due to genetic diseases caused by the inbreeding. Unintended sexual relations between genetically related persons may also arise when either or both biological parents are unknown or uncertain, as in the case of children born as a result of casual or extramarital sexual relations, anonymous sperm donation, surrogacy or adoption. On the other hand, most prohibitions on incest extend the categories of prohibited relationships to affinity relationships such as in-law relations, step relations, relations through adoption, among others.
In societies where it is illegal, some as a victimless crime sees consensual adult incest. Some cultures extend the incest taboo to relatives with no consanguinity such as milk-siblings, stepsiblings and adoptive siblings. Third-degree relatives (such as half-aunt, half-nephew, first cousin) share 12.5% genes, and sexual relations between them is viewed differently in various cultures, from being discouraged to being socially acceptable.
In some societies, such as those of Ancient Egypt and others, brother–sister, father–daughter, and mother–son, cousin-cousin, aunt-nephew, uncle-niece, and other combinations of relations were practiced among royalty as a means of perpetuating the royal lineage. Some writers have described the marriage of Cain to his sister Awan as the first instance of incest. Some societies, such as the Balinese and some Inuit tribes have different views about what constitutes illegal and immoral incest. However, parent-child and sibling-sibling unions are almost universally forbidden.
The justification often given for the incest taboo is the impact of inbreeding on the children of incestuous sex. Children whose biological parents have a close genetic relationship have a greatly increased risk of congenital disorders, death and disability at least in part due to genetic diseases caused by the inbreeding. Unintended sexual relations between genetically related persons may also arise when either or both biological parents are unknown or uncertain, as in the case of children born as a result of casual or extramarital sexual relations, anonymous sperm donation, surrogacy or adoption. On the other hand, most prohibitions on incest extend the categories of prohibited relationships to affinity relationships such as in-law relations, step relations, relations through adoption, among others.