Some people have a "daughter relationship", while others have a "son relationship". What is the reason?

The basic view in the world is that the X chromosome determines the birth of a girl and the Y chromosome determines the birth of a boy. Human sex is determined by the chromosome combination after cell division. There are 23 pairs of chromosomes, including 22 pairs of autosomes and 1 pair of sex chromosomes. In XY-type sex determination, a pair of sex chromosomes of male individuals are heteromorphic and expressed by XY. A pair of sex chromosomes of female individuals are of the same type, denoted by XX; If the father's X chromosome is combined with the mother's X chromosome, the child is a girl; If the father's Y chromosome is combined with the mother's X chromosome, the child is a boy ... Obviously, as a male individual, his chromosome is XY. If he always gives birth to daughters, it is likely that the number of Y chromosomes is reduced or the activity is not enough, which leads to the female combination of XX every time.

Many people find a phenomenon that fathers have the best physical fitness at the right age and are more likely to have boys. However, with the growth of father's age, his physical fitness is not as good as before, and it is easier to have girls. The reason why the older you get, the higher the probability of having a daughter, because the number of sperm with Y chromosome in male semen will decrease with age, so the probability of having a girl is particularly high; The older a woman is, the less alkaline secretions in the uterus caused by aging, and the probability of giving birth to a girl is greatly increased.

In addition, in some occupations, male Y sperm is easy to die, and such occupations are also easy to produce girls, such as captains and taxi drivers. New research shows that engaging in male occupations, such as engineers or accountants, will greatly increase the chances of pregnant women giving birth to boys. Similarly, if you are engaged in female occupations such as teachers and nurses, the baby's gender is likely to be female.

There are many folk sayings about having a boy or a girl. Some people say that if a mother's stomach bulges when she is pregnant, she will give birth to a boy, and vice versa. Others accused the woman of giving birth.

In fact, these statements are groundless. Because at the moment when the fertilized egg is formed, the sex of the child has already been decided, and the decisive factor is the gene. As we know, it is the Y and X chromosomes in male sperm that determine the sex of boys and girls, and they have certain replication functions. Male y sperm is weak, it is easy to have daughters, otherwise it is easy to have sons.