In some cultures, dimples are seen as a sign of beauty or even good luck. But what causes dimples, and why do some people have them while others don't?

Dimples are small, natural indentations in the skin. Around 1 in 5 people have dimples, according to a 2019 meta-analysis in The Journal of Craniofacial Surgery. They are commonly found on the cheeks but can be located on other parts of the body, such as the chin and lower back.

Live Science looked at how these indentations form and whether they can disappear over time.

How dimples are formed

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In people with dimples, however, the zygomaticus major divides into two groups of muscle — one above the corner of the mouth and the other below. This is called a double or bifid ZMj. When the skin moves over the two muscle groups, it forms an indentation, otherwise known as a dimple.

Dimples are passed on genetically, though how is not completely clear. According to a 2015 review in the Innovative Journal of Medical and Health Science, people with one dimpled parent have a 25% to 50% chance of having the indentations, while people with two dimpled parents have a 50% to 100% chance.

"The issue of genetics in dimples has been poorly researched to date, with very little work done in the field," Ross Elledge, a consultant oral and maxillofacial surgeon in the U.K, told Live Science over email. "The overriding theory is that the inheritance is autosomal dominant — only one of a pair of genes is required to code for the presentation of dimples and that this gene can be inherited from the mother or father.”