Close relatives refer to those who have a common ancestor for three generations or less. If they intermarry with each other, it is called consanguineous marriage. Due to the high probability of increasing the risk of illness in the next generation caused by consanguineous marriage, China's Marriage Law stipulates that direct blood relatives and collateral blood relatives within three generations are prohibited from getting married. So consanguineous marriage is illegal, and the marriage registration department will not allow marriage registration procedures to be processed.
The harm of consanguineous marriage
1. Marriage between close relatives can greatly increase the probability of recessive genetic diseases. According to relevant data, the incidence of recessive genetic diseases in offspring of consanguineous marriages is 150 times higher than that in offspring of non consanguineous marriages.
2. The incidence rate of some polygenic genetic diseases in close marriage is higher than that in non close marriage. According to the survey, the incidence rate of polygenic diseases such as congenital heart disease and anencephalic spinal cord fission in the offspring of close relatives is about 1.64%, higher than 0.57% in the children of non close relatives.
3. Children who marry close relatives also have higher early mortality and deformity rates.
4. The offspring of consanguineous marriage will have poorer physical fitness, lighter weight, and shorter height.