Why do some men have chest hair and some don't?

The causes of chest hair are generally divided into two types, one is heredity, and the other is because androgen secretion is too high.

The growth of human hair is mainly controlled and restricted by androgen and estrogen, which can stimulate or inhibit the growth of hair in different parts of the body. Androgen stimulates the growth of beard and chest hair, while estrogen inhibits its growth, so men have beard and chest hair.

So the growth of chest hair is obviously not directly related to age ~ ~ It depends on your androgen ~ ~

Some men don't have chest hair all their lives ~ ~