Dimples—indentations on the cheeks—tend to occur in families, and this trait is assumed to be inherited. Dimples are usually considered a dominant genetic trait, which means that one copy of the altered gene in each cell is sufficient to cause dimples. However, some researchers say that there is no proof that dimples are inherited. Little research has been done to explore the genetics of dimples and it is not known which gene or genes may be involved.
A dimple is an anomaly of the muscle that causes a dent in the cheek, especially when the individual smiles. Some people have dimples in both cheeks, others in just one cheek. Babies are likely to have dimples caused by baby fat in their cheeks. When they lose their baby fat as they get older, their dimples disappear. Other children do not have them at birth, but may develop them later in childhood. In some people, dimples last only until adolescence or young adulthood, while in others they are a lifetime trait.
Dimples that have a similar appearance can occur in successive generations of a family. For example, in one family, it was observed that the siblings, their father, uncles, grandfather, and great-grandfather all had similar-looking dimples in both cheeks. In other families, dimples may occur in a child but are not seen in more than one generation.
Scientific articles for further reading
OMIM: Dimples, Facial (126100)
Wiedemann HR. Cheek dimples. Am J Med Genet. 1990 Jul;36(3):376. PubMed: 2363446.