I've got a third nipple, and I was just wondering why.—Nick

A third nipple is very common actually, Nick. About five percent of humans have a third nipple. Most mammals have mammary lines coming down, right? Multiple things you can suckle off of. If you're a pop, you've given birth to multiple children. So in humans we lost that. We only need to have two because we rarely have more than two babies at once. But sometimes you get remnants. And I've seen quite a few of these.

This is an example of the differences that we have among us, and those differences make us who we are. And most folks who have extra fingers or weird things growing on parts of their body, they're just a remnant from our embryology, from our genetics.

You're born with the extra nipple, and it usually reflects that there was something that went on when you were in your mother's womb that stimulated something in one direction versus the other direction. The only thing that I might worry about is that sometimes people with third nipples have heart problems.

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