Patient's question:
Is it 100% certain that children born from consanguineous marriages will exhibit abnormal behavior or be idiots?Doctor's answer:
Some people say that intermarriage between different ethnic groups increases the incidence of cancer, but this is completely without scientific basis. Modern humans do not have reproductive isolation, nor do they have different species. Whites, blacks, and East Asians are all closely related and belong to the same species. Using an example that everyone can understand, the molecular differences between a black person and a white person may be smaller than the genetic differences between a Beijing person and a Shanghai person. This is what is defined in genetics as the difference between individuals within a species possibly being greater than the difference between individuals of different species.Additionally, for polygenic hereditary diseases such as hypertension, schizophrenia, congenital heart disease, anencephaly, and epilepsy, the incidence rate in children born to consanguineous marriages is significantly higher than in those born to non-consanguineous marriages. For this reason, many countries have banned consanguineous marriages through law. The Marriage Law of China Article 6 states: "Direct blood relatives and collateral blood relatives within three generations are prohibited from marrying." Direct blood relatives refer to the relationships between parents and children, grandparents and grandchildren, and maternal grandparents and grandchildren. Collateral blood relatives within three generations include siblings, uncles/aunts and nieces/nephews, and cousins and their nieces/nephews.
According to surveys, the rate of consanguineous marriages is approximately 0.7% in urban areas and 1.2% in rural areas. In some mountainous rural areas and islands where transportation is underdeveloped, consanguineous marriages are even higher, resulting in a greater prevalence of genetic diseases.