Why do men have nipples?

Answer 1

Why Men Have Nipples
It's left over from early fetal development - at a certain point we were just a fetus with an undetermined gender, and then a flood of hormones came along in utero and told us what gender we were going to be. Nipples are a leftover from that time. Men do have mammary tissue, anyway. Just a tiny, tiny bit of it.

During conception, each fertilized egg starts out with an X chromosome (from the mother) and an X or Y chromosome from the father, which determines their gender. XX will be a female, and XY will be a male. During fetal development, what started out as an undetermined gender gets developed during the fetal stage into a male or a female.

Additional facts

• Most young men grow some breast tissue at puberty which then subsides and there is a fairly common condition called gynecomastia where men grow breasts. This can be treated very successfully by surgery.

• Men can also get Breast cancer which tends to get worse much more quickly than in a woman, so any man past puberty who notices any abnormality, or lumps in their breast tissue, should see a doctor immediately.

• Men have nipples because we all were conceived gender neutral. Somewhere during fetal development we develop into a female or a male. You may notice male and female have all the same "bits" but they differ in size and function. The clitoris for example is the female counterpart to the penis........ovaries to gonads ........and nipples either sit on a pair of breasts or for the male are just there. Also, early embryonic tissue that turns into the uterus in females turns into the prostate gland in males.
  
  

An Inconvenient (maybe) Truth
Male humans can and do produce milk, i.e., they can lactate. Male breasts contain all the structures needed to produce milk.
Further, it is not uncommon to observe lactation in both male and female infants, due to the stimulation they receive from their mother's hormones.

Answer 2

because when they are in the mothers womb the sex is not determined until they are late on so therefore the hormones haven't got enough time to get rid of the nipples!! plus

BUT IMAGINE MEN WITHOUT NIPPLES THEY'D LOOK ALIEN!!!!

Answer 3

So we can tap our fingers on them while we sing. :)

David Wesson.