Incest

Incest generally refers to sexual relations between close family members, such as brother and sister or parent and child. It is a criminal offence and an impediment to marriage in most modern countries, as well as being against most modern religions. The definitions of "close family member" and "sex" vary widely.

In the United States and other industrialized countries,incest is generally used to refer to forbidden sexual relations within the family. Incest is most frequently a form of child sexual abuse committed by parents of both sexes. And while it is usually perceived as an act done by a father against his daughter, this is yet another myth surrounding the practice. It is widely, but by no means universally, agreed that incest by parents should be illegal. Some societies, notably India in the 1920s, consider incest an inescapable fact of life.

However, there is also the much rarer phenomenon of consensual incestuous relations between adults, such as between an adult brother and sister. This is illegal in most places, but these laws are sometimes questioned on the grounds that such relations do not harm other people (provided the couple have no children) and so should not be criminalised. Artificial insemination and distant adoption have compounded these problems. There are known cases of people having romances, or even marrying, only to later find out they are closely related.

In many societies some forms of sexual contact between close family members is encouraged. For example, one practice formerly common in Bali was for mothers to sexually stimulate infants.