Patient's question:
Can children born from consanguineous marriage inherit if they get married?Doctor's answer:
Hello: Friend, consanguineous marriage refers to marriage between direct blood relatives or collateral blood relatives within three generations. Consanguineous marriage can easily lead to fetal malformations and mental retardation, so it should be prohibited. In genetics, the transmission of genes can distinguish different levels of kinship. Let's first look at the probability of genes being the same between siblings (twins): If a person has gene A, there is a 1/2 chance that it is inherited from the father, and similarly, the person's siblings also have a 1/2 chance of having this gene from the father. Therefore, from the perspective of transmission from the father, the probability of siblings sharing the same gene is 1/4. Similarly, from the perspective of transmission from the mother, the probability of siblings sharing the same gene is also 1/4. Since a person's gene is either inherited from the father or the mother, the total probability of siblings sharing the same gene is 1/2. Anyone with a 1/2 chance of sharing the same gene (such as parents and children, siblings) is called a first-degree relative; the probability of a person sharing the same gene with their grandparents, great-grandparents, uncles, aunts, nieces, and nephews is 1/4, making them second-degree relatives; the probability of a person sharing the same gene with their first cousins and second cousins is 1/8, making them third-degree relatives. What are the harms of consanguineous marriage? According to analysis, consanguineous marriage mainly has the following drawbacks: (1) High incidence of genetic diseases: 36% of genetic diseases are caused by parent, first cousin, and second cousin marriages. For example, a common condition like cleft lip has an incidence rate of only 0.17% in the general population, but the incidence rate among consanguineous marriages can be as high as 4%. The offspring of consanguineous marriages are several times more likely to suffer from mental retardation, congenital malformations, and various genetic diseases compared to those of non-consanguineous marriages. (2) High mortality rate: The mortality rate of children from consanguineous marriages is much higher compared to those from non-consanguineous marriages. (3) Shorter body height, lighter weight, and smaller head circumference: Compared to infants born from non-consanguineous marriages, infants born from consanguineous marriages tend to be shorter, lighter, and have smaller head circumferences. Generally speaking, the closer the blood relationship, the higher the incidence of genetic diseases, and the farther the blood relationship, the lower the likelihood of suffering from genetic diseases. Of course, not all children born from consanguineous marriages will suffer from genetic diseases; some may be both healthy and intelligent. Children born from non-consanguineous marriages may also suffer from congenital heart disease, mental retardation, albinism, but this is extremely rare.