Children of close relatives

The main reason for close relatives to get married is that they have some relatives who have a common ancestor within three generations. If they marry each other, it is a marriage between close relatives. Couples who get married in a close relationship may obtain certain genes from their common ancestor and pass them on to their children. If the airplane case involves recessive inheritance, his children will have some problems. The recent divorce mainly increases the risk of some people developing genetic diseases.

At the same time, the probability of some overlap or identical genes in the actual genes is also relatively high. Therefore, by taking the genes given to individuals or combining them with the many genes of the opposite sex they carry, several common and real genetic diseases will occur.

According to experts' estimates, every normal person may carry several or even a dozen harmful recessive alleles. Inbreeding will give these recessive alleles more opportunities to meet and cause genetic abnormalities. The human nuclear genome comes half from the father and half from the mother. In the case of consanguineous marriage, the chance of two identical problematic genes combining together is much greater than that of people who are not consanguineous. How big is the risk of inbreeding? Let's calculate it based on the following marriage patterns:

If there is a first-degree cousin-to-first-degree cousin marriage between the first cousin and the second cousin, the consanguinity index is 1/32, and so on for other types. Assume that the proportion of a genetic disease in the population is 1/1000:

The risk of disease in offspring of non-consanguineous marriage is 1/1,000,000 (one in a million);

The risk of disease in offspring of second-degree cousin marriage is 1/128,000

The risk of disease in offspring of first-degree cousin marriage is 1/32,000

The risk of offspring from a brother-sister marriage is 1/8000

Compared with non-consanguineous marriage, the risk of second-degree consanguineous marriage is 8 times higher; the risk of first-degree consanguineous marriage is 31 times higher; and the risk rate of brother-sister marriage is 125 times higher than normal random marriage!

The above are some common effects of marriage between close relatives. Through the transmission of genes or the combination of many genes of the opposite sex carried by individuals, hundreds of millions of common and real genetic diseases will be produced. Hypertension is a genetic disease that can cause congenital diseases for some close relatives to marry. It is more obvious.