According to the "Marriage Law" of our country, the marriage of direct blood relatives and collateral blood relatives within three generations is prohibited, so the three generations and within three generations belong to the marriage of close relatives.
First, several generations count as close relatives marry
Consanguineous marriage refers to the marriage of three or less generations of people who share a common blood relationship. The specific algorithm is that from the common ancestor of the two sides, it is remembered as the first generation, and then it is counted down from generation to generation, and the number of generations is the generation of marriage.
For example, when Cousins marry, the maternal grandmother of both sides is the first generation, the mother of both sides belongs to the second generation, and the marriage of Cousins belongs to the third generation, so the marriage of Cousins belongs to the marriage of close relatives.
Second, the harm of consanguineous marriage
1, the marriage of close relatives is illegal, the marriage registration office is not to apply for marriage registration, and if you get a marriage certificate, the follow-up was found, it is also an invalid marriage.
2, the offspring of consanguineous marriage have a higher death rate. Since both sides will have a high probability of acquiring the same disease-causing gene from a common ancestor, the offspring will have a higher probability of disease than the average child, and the death rate will be relatively high.
3, consanguineous marriage will greatly increase the probability of recessive genetic diseases. According to relevant data, the recessive genetic diseases of inbred offspring will be 150 times that of non-inbred offspring.
4, the incidence of some polygenic genetic diseases of consanguineous marriage is higher than that of non-consanguineous marriage. According to the survey, the incidence of polygenic diseases such as congenital heart disease and spinal cord fission of anencephalic offspring is about 1.64%, which is higher than 0.57% of non-close married children.