The marriage system has been with humans for thousands of years. In primitive society, marriage did not exist at that time. As long as we like each other, we can have children together. After humans enter civilized society, this phenomenon disappears.
In a civilized society, ethical concepts were formed in people's minds, and monogamy became everyone's consensus, and a beautiful love vision of a lifetime and a pair of people has also become a life that all mankind has longed for.
However, you cannot get married casually. Intermarriage is prohibited between close relatives because this will cause fetal deformities. However, in ancient times, cousin married a cousin, but why are there few deformities rarely? The reason is actually very simple.
The harm of in-kind marriage
In-kind marriage refers to the combination between people with blood relationships within three generations. In ancient times, when the proportion of biological knowledge popularization was not high, coupled with some superstitious behaviors, people did not realize the harm of in-kind marriage.
In ancient times, it was a society based on agricultural civilization. In order to resist the risks of life, people often gathered together to keep warm, which led to the development of clan culture. If a clan or a family wants to develop stably, they rely on marriage.
People are also subject to some superstitious sayings, such as getting married means marrying your own relatives, the elder brother marrying his younger brother, aren’t the children born in this way more kin?
However, with the advancement of science and the more and more deformed children in society, people realized something was wrong. Finally, they found out that marriage in close relatives is the culprit of deformed children.
Since each person's genes are different, if the blood relationship is the same, the probability of recessive pathogenic genes in the gene becoming dominantly expressed will greatly increase.
For example, people in a family have the recessive gene of heart disease, but they have not been expressed in several generations. Once people in this family get married and have children, their children are likely to suffer from heart disease.
According to WHO research, each of our genes carries at least five to six pathogenic genes. If we marry and have children with people who are not related to blood, this pathogenic gene is also different because of the different genes between each other, and the children born are naturally healthy.
But if a close relative gets married, the pathogenic genes in both parties are the same. After the two parties combine, the pathogenic genes in each other's bodies will become homozygous and expressed in the children. The children born with congenital diseases are likely to be born, which is also the reason why the mortality rate of children married with close relatives is high.
Although it is just a question of probability, when the probability is very high, it becomes a positive answer to get married and give birth to a deformed child.
The probability of giving birth to a child with a congenital disease is one in one million after marriage, but the marriage of a close relative becomes one in one in one in one in one thousand. If the cousin or cousin is combined, the probability of the child they have given birth to is one in one in three thousand.
The most terrifying thing about getting married in close relatives is that they are born by a parent and a parent, and their genes are highly similar. The probability of giving birth to a sick child is one in 8,000. Such data is terrifying.
After entering the modern era, my country's public health level has been continuously developed. In order to implement the spirit of "eugenics", the law stipulates that intimate marriages within three generations are strictly prohibited. It can be said that the problem of intimate marriages has been solved from the source.
In the news, especially at the end of the last century, we often hear news about relatives getting married and giving birth to deformed children in remote areas, but we seem to have never heard of deformed children in ancient times, which is very strange.In ancient times, close relatives were very common behavior, but why did they not give birth to deformed children?
Ancient close relatives got married
In fact, it was a huge misunderstanding that ancient people did not have deformed children when they got married, because in ancient times they were just in the surface marriage, but in fact they were not in close relatives.
For example, there are two major families in Haining, Zhejiang, namely the Chen family and the Cha family. These two families are large families that have lasted for more than five hundred years since the Ming Dynasty. Many people in this family got married in close relatives, but their descendants are healthier than the other.
Why is this? Can these two families have better genes than other Chinese? In fact, it is not true, mainly because their kinship is already very far away.
As mentioned earlier, close relatives do not necessarily give birth to deformed children, but the probability is relatively high, and there is still a very small probability of giving birth to healthy children. In the early days of ancient times, due to the small population, marriage to close relatives was an inevitable problem at the beginning.
If a close relative gives birth to a healthy child after marriage, the child will grow up and scatter, and the child between his or her relatives will be combined, and the probability of offspring being sick will decrease by 30 times.
After the first-degree close relatives get married, they come to the second-degree close relatives to get married. The risk of giving birth to sick children is eight times lower than the previous generation, so if they continue to give birth to this, the blood relationship in the family will be diluted.
We often have this kind of experience, that is, the child born by the father's distant sister. If it is older than us, we should call our cousin, or the child born by our grandmother's cousin, and our parents' cousin, and their children are the same as us. We have a cousin relationship with them, but there is no blood relationship anymore.
This is how ancient families were established. Although everyone has the same surname and even traced the root of the source, everyone's blood relationship has long been less close. Even if they are combined again, the probability of giving birth to a healthy baby is very high.
Another thing is that in ancient times, medical technology was underdeveloped, birth, old age, sickness and death were common. In remote areas, many people have very short lifespans.
Even if someone gives birth to a deformed fetus, no one will think that this is a big deal, just treat it as a general matter, and will not record it as important information. This also creates a stereotype of no deformed children in ancient times.
In-kin marriage products in history
In history, many celebrities are the products of in-kin marriages. For example, Darwin, a great scientist who founded the theory of evolution, his wife is his cousin. The two gave birth to a child after marriage. Three of these children died prematurely, and the remaining seven children suffered from infertility.
Darwin also woke up from his own examples. Look, although the chance of giving birth to healthy children is not low, and seven of the ten children survived, they all had infertility genetic defects, which finally made Darwin amazing.
Coincidentally, Einstein, who founded the theory of relativity, also got married in close relatives. His second wife was his cousin. The two gave birth to a son, but this son was finally diagnosed with congenital schizophrenia, which made Einstein suffer for a lifetime.
