Extra or supernumery nipples (polythelia) are fairly common occurring in about 5% of men and 2% of women. They occur along the embryonic milk lines that run from the armpit to the groin in all mammals. They are often mistaken for moles because they are quite small. They usually appear on just one side but can be paired either above or below the normal nipple. In this rare extreme example of an extra nipple, the nipple=areolar complex is fully formed and sits above the normal nipple. Most extra nipples, however, are quite small, often appearing a small brow dot or ‘mole’ sitting below the breast mound or chest on the abdominal wall.
Interestingly, they occur in men far more frequently than in women by a near 5:1 ratio. (1:18 male births, 1:50 female births ) Historically an extra or third nipple was believed to be a sign of increased femininity or even being a witch. (suckling the devil) Their common occurrence if exemplified by having them occur in famous people…the actor Mark Wahlberg is but one example.
Dr. Barry Eppley
Indianapolis, Indiana