Is a dimple on one cheek rare?

The presence of a double or bifid zygomaticus major muscle results in a gap which creates dimples. Wish all deformities be seen as beauty !! Is it rare to be both left-handed and have one single dimple in the cheek? yes, it is rare.

Why do I have a dimple on one cheek but not the other?

Cheek dimples can be found on the sides of the mouth. You can have a dimple on both sides of your mouth or on just one side. You’ve probably noticed that some people have cheek dimples and others don’t. That’s because cheek dimples are formed by differences in the muscles and skin of the face.