Prohibited degree of kinship
The probable biological basis for the generality of the marital incest taboo is that matings between close relatives lead to progeny that tend to experience inbreeding depression, due largely to the increased expression of recessive deleterious mutations.
According to the official explanation, the calculation of degree of consanguinity in China is similar to Roman civil law with some difference.
Aforementioned "collateral relatives by blood up to the third degree of kinship" include: In Imperial China (221 BCE to 1912), marriage between first cousins was partially allowed.
However, among other exceptions, marrying the child of your paternal uncle was strictly prohibited, as such a marriage was seen as one between siblings as each of the couple bore the same family name.
[5] The method of calculation was also changed to simply count the number of generations back to the common ancestor.
[9] The list was enacted by the Marriage Act 1949 which with significant changes continues to apply in England and Wales.
Article 14 of the Family Code of the Russian Federation stipulates that marriages between close relatives (determined by a direct bloodline) are prohibited, but no penalty is specified.
The exact rules depend on the traditions of the concrete regions and may vary despite a formally written law.
[17] Since the 13th century, a ban on marriages between close relatives has been formalized by the Russian Orthodox Church in the nomocanon, referred to as Kormchaia.
[18] In terms of sexual relationships and intercourse in rural Russia, the practice of Snokhachestvo was widespread in the 16th and 18th centuries.
[19][18] Statutes in the U.S. state of Georgia disqualify a juror if that person is related "by consanguinity or affinity" to any party "within the sixth degree as computed according to the civil law".
690 (1853), stated the long-standing, common-law rule disqualifying a venireman (juror) who is related, within the ninth degree of consanguinity or affinity, to a party to a suit.
1 Some states recognize marriages performed elsewhere, especially when the spouses were not residents of the state when married.