Why do men have nipples ?

There are lots of speculation about it, it is true that though women are having a logical purpose but why do men having nipples, some thought that it is the sign of being a mammal, some believe males are failed female, all unborn creature having a tendency to be shape up as a female but due to some reason they failed to be so and turned out as male.

According to medical science male breast can also produce milk and can  develop female breast diseases like breast cancer.

As a common factor some quantity of  female hormone estrogen is always present in the body of each and every men, and due to hormonal dis-balance (by any disease or condition) men can experience breast tissue growth and produce milk.

Medically enlargement of breast in men with other female like conditions is known as gynecomastia.

Any embryo be it a male or female at the preliminary stages starts with similar cells and tissues hence they have some common body parts that is the logical reason why both sexes are having nipples.