Savannah: Harry Styles has more than two nipples, and he is not alone. So do about 4% of people. It's because of how breast tissue forms in utero. Developing embryos have two specialized skin cells at the front of their chest that copy themselves over and over as they migrate down to the groin. This V-shaped path from your armpits to your pelvis is called the "milk line." And most of that line naturally goes away, with the exception of what develops into your breast tissue. But when it doesn't, you can end up with bonus nipples called "ectopic" or "accessory breasts." That's why Harry Style's ectopic nipples are close to his...uh...other ones.

Now, this tissue can vary from person to person; some are barely developed while others are fully developed. And they're breast tissue, so they can even enlarge during lactation the way breasts generally do. [sings] "In this world...it's just tissue."

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