Real insect sex relations
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.
Brazilian law, by the Article 1521 of the Civil Code, also extends the invalidity of marriage between parents and children to grandparents and grandchildren or any other sort of ascendant-descendant relationship (both consanguineous and adoptive), parents-in-law and children-in-law even after the divorce of the earlier couple (see affinity), as well as to stepparents and stepchildren, and former husbands or wives to an adoptive parent who did this unilaterally (regarded as an equivalent, in families formed by adoption, to stepparents and stepchildren); and extends the invalidity of marriage between siblings to biological cousin-siblings.
It also formerly prohibited the avunculate marriages and extended the prohibition for marriage between siblings to half-siblings, both cited above, but the Decrete Law 3.200/1941 made marriage possible for those non-ascended/descended in consanguinity of third degree (25%) provided both have health checks.
The prohibited relationships are grandfather-granddaughter, father-daughter, brother-sister and mother-son.
Punishment is up to 20 years' imprisonment for male offenders and up to 14 years' imprisonment for female offenders.
The Laws regarding incest in the United States article summarizes these laws for individual U. In most states, sexual activity between a lineal ancestor and a lineal descendant (parent, grandparent with child or grandchild), siblings (brother-sister) and aunt-nephew, uncle-niece is penalized as incest. Rhode Island has repealed its criminal incest statute, The most severe penalties for incest are in Massachusetts, Virginia, Texas and Oregon, which punishes incest with up to 20 years in prison, Georgia where a penalty for incest is up to 30 years in prison, Wisconsin where the penalty for incest is up to 40 years in prison, and in the states of Nevada, Montana, Idaho and Michigan where a penalty of up to life imprisonment for incest may be given.
In some states, sex between first cousins is prohibited (see cousin marriage law in the United States by state for cousin sex, as well as cousin marriage, being outlawed in some states).
When incest involves an adult and a child, it is usually considered to be a form of child sexual abuse.
The law does not cover sexual intercourse with more distant relatives, such as an aunt, uncle, niece, nephew and cousin.
It only addresses male-on-female and female-on-male sexual intercourse, and it appears that consensual same-sex incest is not illegal.
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.