Question: why do males have nipples

Andrew McKinley answered on 17 Jun 2010:

Nipples are a characteristic common to both genders, but are only functional in the mature female of the species. In men, they’re purely for decoration!
As to why we have them; whether we are to be male or female is decided at conception – depending on what sort of sperm fertilises the egg, whether it is an X-type sperm (resulting in a girl) or a Y-type sperm (resulting in a boy). This endows us with the primary sexual characteristics, while the secondary characteristics occur in response to hormones released during adolescence.
In men, the nipples are not functional, but men do have dormant mammary glands; if exposed to doses of oestrogen (the female hormone) these will develop into breasts. Even without this, some men can develop what is technically known as breast cancer.