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A small child with dimples.

Dimples are visible indentations of the skin, caused by underlying flesh, which form on some people's cheeks when they smile.

Dimples are genetically inherited and are a dominant trait.^[1] Dimples on each cheek are a relatively common occurrence for people with dimples. A rarer form is the single dimple, which occurs on one side of the face only. Anatomically, dimples may be caused by variations in the structure of the facial muscle called zygomaticus major. Specifically, the presence of a double or bifid zygomaticus major muscle may explain the formation of cheek dimples.^[2] This bifid variation of the muscle originates as a single structure from the zygomatic bone. As it travels anteriorly, it then divides with a superior bundle that inserts in the typical position above the corner of the mouth. An inferior bundle inserts below the corner of the mouth.

Dimples are considered attractive in some cultures. Babies commonly have dimples, but sometimes these disappear (or become less noticeable) as the muscles lengthen with age; consequently, dimples are often associated with youth.

Actor Kirk Douglas exhibits a cleft chin.

Some people have a dimple on their chins, known as cleft chin. Like cheek dimples, chin dimples are inheritable and have a varying degree of prominence. For example, while Kirk Douglas has a very conspicuous cleft chin, his son, Michael Douglas has a much less visible cleft chin. Females generally have less conspicuous cleft chins than males, like Elisha Cuthbert.^[3]

The groove of the cleft chin is not just skin-deep, but also on the jawbone, as a groove in the vertical midline of symphysis menti and the soft tissue above it. It is probably the result of incomplete fusion between the left and right halves of the lower jaw during embryologic development.^[4]

• List of Mendelian traits in humans

• Curious about Dimples
• Possible inheritance of dimples
• What causes dimples?