A chin dimple, also known as a cleft chin, is a Y-shaped dimple in the middle of the chin that is genetic and inherited from parents, even if they do not have a visible cleft. During fetal development, the two sides of the jaw do not fuse completely, causing the gap that creates the dimple. Chin dimples are harmless and do not involve muscles, unlike cheek dimples, which are caused by the zygomaticus major muscle splitting into two during fetal development.