Whether it is in China or other countries, there is basically a history of marriage, and this phenomenon is actually related to power. In order to maintain their power, the ancients believed that only blood relatives would not steal their own things, so that the status of the dynasty or family became more stable. If the people around you are relatives and the heirs are also relatives, there will naturally be fewer enemies, so the marriage of close relatives has been promoted.
From a modern scientific point of view, children born of close relatives are prone to underdevelopment, even deformity. The fertility history of ancient people is not short, they cannot be unaware of the harm of close fertility, so this way of marriage was initially only popular in the royal family, and later introduced to the folk, and the families with better family conditions are very disgusted with the marriage of close relatives. So isn't the royal family afraid that their descendants are mentally retarded? The reason is actually quite simple.
Polygamy
In the past few thousand years, China has been a country ruled by male power, as long as the man has the conditions, he can marry many wives, and the general rich and noble families will marry 3-5 women, and there are more women in the emperor's harem. Many of these women are related to the emperor, more and more benefits, marry more women, give birth to more children, the number of surviving children also increased, want to choose an heir, focus on the body integrity, good health, intelligent children on the line, so those due to inbreeding and deformity of the child can basically be discharged.
Second, the huge clan relationship
In ancient Chinese history, people with the same surname were usually inextricably linked, and the greater the number of clans, the greater the network of relationships. For example, some women marry to a remote place, but also can find their own relatives, in fact, this is affected by the ancient form of blind date, every New Year's Festival, everyone likes to visit relatives, not only can celebrate the festival, but also by the way to meet a few suitable people. Therefore, no matter where the entire clan marries, there will be a chance to meet with relatives, the relatives mentioned here are not necessarily related by blood, belonging to the same clan can also be called relatives, which reduces the chance of close relatives marrying and giving birth to deformed children.
3. No heirs were left
The two reasons mentioned above can only be said to reduce the probability of deformity, which does not mean that there must be none, but the last reason can ensure that there are no deformed and mentally retarded children. Even if you are married to a close relative, if you do not have a child with your other half, the chance of a mentally retarded child will be zero, and you do not have to worry about the problem of underdevelopment of the child.
From the above three reasons, we can know that the phenomenon of marriage between close relatives in ancient times was very common, and it was popular among rich and noble families and royal families, but overall, the number of children with intellectual disabilities is still relatively small. The statistics of the data are related to the base, as long as there are enough children born, they are not afraid of the impact of the mentally retarded children on themselves. In addition, because of the existence of clans, the concept of relatives is different from our modern understanding, so in ancient times, it was not necessarily a blood person who was classified as a relative. If you and your partner don't even have children, then you don't have to care about the mentally retarded children, and it doesn't matter if close relatives marry. Compared with ancient times, modern people are much luckier, not only know basic scientific knowledge, but also legal protection, and the marriage of close relatives is not allowed.