Laws regarding incest (i.e. sexual activity between family members or close relatives) vary considerably between jurisdictions, and depend on the type of sexual activity and the nature of the family relationship of the parties involved, as well as the age and sex of the parties. Besides legal prohibitions, at least some forms of incest are also socially taboo or frowned upon in most cultures around the world.
Incest laws may involve restrictions on marriage, which also vary between jurisdictions. When incest involves an adult and a child (under the age of consent) it is considered to be a form of child sexual abuse.
Degrees of relationship
Laws regarding incest are sometimes expressed in terms of degrees of relationship. The degree of relationship is calculated by adding the number of generations back to a closest common ancestor of each individual. Consanguinity (but not affinity) relationships may be summarized as follows:
Most laws regarding prohibited degree of kinship concern relations of r = 25% or higher, while most permit unions of individuals with r = 12.5% or lower. In 24 states of the United States, cousin marriages are prohibited. Also, most laws make no provision for the rare case of marriage between double first cousins. Incest laws may also include prohibitions of unions between biologically unrelated individuals if there is a close legal relationship, such as adoption or step relations.
World map
Table
Countries in Africa that criminalize incest
Zimbabwe
In Zimbabwe, most forms of incest are illegal and an offender is currently liable to a fine up to or exceeding level fourteen (about US$5000) or imprisonment for a period not exceeding five years or both. Incest is classified as "sexual intercourse within a prohibited degree of relationship". A prohibited degree of relationship would be that of a parent and their natural or adoptive child, a step-parent and their step-child, whether the step-child's parent and step-parent are married under the Marriage Act [Chapter 5:11] or the Customary Marriages Act [Chapter 5:07], or are parties to an unregistered customary law marriage, and whether or not the child was over the age of eighteen years at the time of the marriage; a brother and sister, whether of whole or half blood; or an uncle and his niece; or a grand-uncle and his grand-niece; or an aunt and her nephew; or a grand-aunt and her grand-nephew; or a grandparent and their grandchild and any person and their first or second cousin. In cases of first and second cousins an individual charged with such a crime can raise a defense that the cultural or religious customs or traditions of the community to which they belong does not prohibit marriage between first or second cousins; or in the case of a person who is a member of a community governed by customary law, that the cultural or religious customs or traditions of the particular community to which they belong does not prohibit marriage between first or second cousins.
Countries in the Americas that criminalize incest
Canada
Under Canadian federal law, incest is defined as having a sexual relationship with a sibling (including half-sibling), child/parent or grandchild/grandparent, requiring knowledge of the existence of the blood relationship. Everyone who commits incest is guilty of an indictable offence and is liable to imprisonment for a term of not more than 14 years and, if the other person is under the age of 16 years, to a minimum punishment of imprisonment for a term of five years.
United States
Laws regarding incest in the United States vary widely among jurisdictions regarding both the definition of the offense and penalties for its commission. The laws regarding incest in the United States article summarizes these laws for individual U.S. states and the District of Columbia.