Although in 1981, China promulgated the Marriage Law of the People’s Republic of China, which clearly stipulates that intermarriage between blood relatives in the direct line and collateral blood relatives within three generations is prohibited, today, there are still some regions and countries where the phenomenon of consanguineous marriage exists, and some people even think that this can keep the bloodline “pure”. But the facts clearly give them a “smack in the face”! The children born in consanguineous marriages, both in terms of physical development and intellectual development, have a tendency to be inferior to the offspring born in non-consanguineous marriages, and most of them have different degrees of abnormalities, such as birth defects, genetic diseases, and even premature death. Instead of maintaining the “nobility” of the bloodline, the quality of the population is reduced. In summary, the harm of consanguineous marriage mainly has the following five aspects: 1, the rate of miscarriage of consanguineous marriage is significantly higher than that of non-consanguineous marriage; 2, the mortality rate of newborns and infants of consanguineous marriage is also significantly higher than that of non-consanguineous marriage; 3, the incidence of birth defects in newborns of consanguineous marriage is significantly higher than that of non-consanguineous marriage; 4, the incidence of polygenic genetic diseases and recessive genetic diseases are significantly higher than the possibility of non-consanguineous marriages; 5. affect the ethical relations and morality of our society and violate the Marriage Law of the People’s Republic of China. In medical genetics, it is common to refer to some individuals who share a common ancestor within 3-4 generations as close relatives. It is customary in China to judge inbreeding from whether both parties have a common great-grandfather as the criterion. In nature, self-pollinated plants are often inferior from one generation to the next and are eventually eliminated, while heterogeneous pollination is often more superior, as is human reproduction. Each normal person may carry several or even a dozen harmful recessive genes, and close relatives, because of their genetic similarity, will give these genes more opportunities to meet and produce genetic abnormalities. However, it should be reminded that not 100% of the offspring born from consanguineous marriages will have problems, only that the probability of causing abnormalities will be very high. Therefore, avoiding consanguineous marriages is the best means of preventing the risk. In addition, even if the marriage is not consanguineous, there is still a certain risk of childbirth and preconception and prenatal testing should never be ignored. There are nearly 30,000 genes in humans, and it is impossible to determine exactly which disease-causing genes each person carries, so it is still impossible to specify the full range of reproductive risks. However, with the development of whole genome sequencing technology, couples who are married and are preparing for pregnancy can consider whole genome sequencing to test the genomes of both partners, along with other preconception and prenatal tests to reduce the risk of having a child with the disease. Others have concerns about the dangers of consanguineous marriage: “My parents are consanguineous, but there is nothing abnormal about me, so will there be a problem with the child born from my marriage?” Here you can first rest assured. A couple whose parents are consanguineous, but whose parents are not consanguineous and both of whom are normal, will have a consanguineous marriage that will not affect the health of the children born to that couple, and the chances of their children having birth defects are comparable to those of the general population. References: [1] Chen Wenfu. Genetic analysis of the hazards of consanguineous marriage [J]. Journal of Henan College of Education (Natural Science Edition),2001,10(2):43-45. [2]Tan Yeguo. Genetic counseling on consanguineous marriage[J]. Chinese Journal of Medical Genetics,2016,33(1):108-110.