Cousin marriage refers to a form of marriage in which both parents are brothers and sisters born of the same blood line. It is a close relative marriage. According to Article 7 of China's Marriage Law, marriage is prohibited for direct relatives and collateral relatives within three generations. Marriage between close relatives poses a great threat to human reproduction, eugenics, and the health of offspring, and is one of the legal situations in China that prohibits marriage.
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.