Men have nipples because nipples develop early in the womb before the sex of the embryo is determined. Both male and female embryos initially develop nipples as part of a common blueprint, and nipples form before the Y chromosome triggers male-specific development around the sixth to seventh week of pregnancy. Essentially, men have nipples because the structure is laid down before sexual differentiation occurs, and nipples usually remain after that point. While men’s nipples don’t serve the same breastfeeding function as women’s, they are not entirely functionless. They contain nerves and can be sensitive to stimulation, often contributing to sexual arousal. Men also have the same nipple glands and tissues, though these do not develop for lactation like in women. Occasionally, men can produce nipple discharge or even lactate due to hormonal or medical conditions, but this is rare. In summary, men have nipples as a byproduct of embryonic development, shared early between sexes, and their nipples may have a sexual function related to sensitivity but not lactation.