An ancient custom in China (saying that Huang and two surnames can't get married)

It is a requirement of eugenics to prohibit consanguineous marriage. The development of human sexual relations has proved that intermarriage between relatives who are too close in blood is easy to pass on physical defects to future generations, affecting family happiness and endangering national health. Marriage between unrelated clans can create a more physically and intellectually robust race. Therefore, the laws of all countries prohibit consanguineous marriage within a certain range. For example, Japanese civil law prohibits collateral blood relatives from getting married within three degrees. The Swiss Civil Code prohibits marriage between lineal blood relatives, brothers and sisters of full blood relatives or half blood relatives, uncles, uncles and uncles, aunts and uncles. China has long said that "men and women have the same surname, but they are born the same". Since the Western Zhou Dynasty, marriage with the same surname has been forbidden. In the Tang dynasty, marriage with the same surname was sentenced to two years in prison. According to the laws of Ming and Qing dynasties, people with the same surname get married, each employee is 60, and divorced. The marriage of the same surname was changed to the marriage of the same clan in the late Qing Dynasty. The Civil Code of Taiwan Province Province, China prohibits the following relatives from getting married:

(1) lineal blood relatives and lineal in-laws;

(2) collateral blood relatives are within the sixth degree, but those collateral blood relatives established by adoption are peers;

(3) kinship within five degrees of collateral in-laws, peers are not subject to this restriction.

After the founding of New China, 1950 Marriage Law prohibited direct blood relatives, brothers and sisters, half-brothers or half-sisters from getting married, and stipulated that collateral blood relatives were prohibited from getting married within five generations. 1980 Marriage Law not only retains the prohibition of direct consanguineous marriage, but also explicitly prohibits collateral consanguineous marriage within three generations. The revision of the marriage law has not changed the scope of prohibiting consanguineous marriage. In other words, there are two kinds of blood relatives who are forbidden to get married in the marriage law:

(1) lineal blood relatives. Including parents and children, grandparents, grandparents and grandchildren, grandchildren. In other words, a father can't marry his daughter, and a mother can't marry her son as a husband. Grandpa can't marry a granddaughter, and grandma can't marry a grandson.

(2) collateral blood relatives within three generations. Including: (1) brothers and sisters of both parents (including half brothers and sisters). That is, children of the same parents cannot get married. (2) uncles, uncles, aunts, aunts and nephews of different generations. Is that an uncle can't marry his brother's daughter; Aunt can't marry her brother's son; Uncle can't marry his sister's daughter; Menstruation can't marry my sister's son.

(Excerpted from Interpretation of Marriage Law of the People's Republic of China)