Orlando Bloom might have the nicest dimples around, but glance at his chin and you’ll notice a lack of a dent. Look at Demi Lovato’s chin though and you’ll see a cleft, almost like an indent there. How can somebody have one kind of dimple but not the other? And what causes dimples in the first place?
Cheek dimples are the result of a muscle in the cheek, the zygomaticus major, splitting in two. Before birth this muscle can split into a superior bundle that is positioned above the corner of the mouth, and an inferior bundle, below the corner of the mouth. This splitting creates a hammock sort of effect where skin can hang in slightly between the two bundles. When you smile, the muscles contract and the dimples are more prominent due to the increased skin tension. Chin dimples on the other hand, have nothing to do with muscles.
Cleft chins, or butt chins are they’re colloquially called, are a result of an unfused jaw bone. The skin over the tiny gap is indented, creating the dimple. If you ever feel a cleft chin, you can actually feel the gap, but don’t worry, this anatomical feature is harmless. It is dominant genetically though, so your kids might face a few inevitable ‘butt face’ insults.