“A man is an adult male human. Prior to adulthood, a male human is referred to as a boy.
Like most other male mammals, a man’s genome typically inherits an X chromosome from his mother and a Y chromosome from his father. The male fetus generally produces larger amounts of androgens and smaller amounts of estrogens than a female fetus. This difference in the relative amounts of these sex steroids is largely responsible for the physiological differences that distinguish men from women. During puberty, hormones which stimulate androgen production result in the development of secondary sexual characteristics, thus exhibiting greater differences between the sexes. However, there are exceptions to the above for some transgender and intersex men.” wikipedia