"The father decides whether a boy or girl is a boy"? A mysterious journey into sex chromosomes

Why are some babies boys and some girls when they all grow up in their mother’s belly?

This question starts with the mysterious sex chromosomes...

"It is up to me to decide whether to have a boy or a girl."

The mysterious sex chromosomes

What exactly are chromosomes? Chromosomes are actually carriers of genetic material in humans, and exist in various somatic cells such as blood, bones, and muscles.

A normal human body has 23 pairs of chromosomes (46 chromosomes), one from the father and one from the mother. Among them, one pair is directly related to our gender - X chromosome and Y chromosome, which are called sex chromosomes.

Normally, sex chromosomes exist in pairs in the human body. The mother's sex chromosomes are composed of two X chromosomes, and the father's sex chromosomes are composed of one X and one Y chromosome.

Who determines gender?

Don’t think that you came out of your mother’s “belly” and your gender is determined by your mother. In fact, on the contrary, your gender is determined by your father.

The sex chromosomes of the mother's egg only have X chromosomes. The sex chromosomes of the father's sperm carry X chromosomes and Y chromosomes. They will enter the mother's body at the same time and randomly combine with the egg. If the sperm carrying the X chromosome combines with the mother's egg first (X+X), a girl will be born; if the sperm carrying the Y chromosome combines with the mother's egg first (X+Y), then a boy will be born.

In other words, your gender is determined by the chromosomes given by your father. More precisely, it is determined by whether the sex chromosome carried by your father's sperm is X or Y.

In nature, the combination of different sperm and eggs is random. Every life, whether it is a boy or a girl, is precious and unique. We must learn to cherish ourselves and respect others.

Source: Chongqing Institute of Population and Family Planning Science and Technology

Author: Xu Xiaoou

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