Cousins belong to the same grandparents and fall under the category of consanguineous marriage. According to Article 7 of China's Marriage Law, marriage registration is not allowed. Even if a marriage is registered by chance, it will be treated as an invalid marriage if discovered.
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.