Are dimples and cleft-chins (aka dimple chins, butt chins) genetic? How rare are cleft chins or dimples?
Professor McDonald, citing limited research, concludes dimples have been mislabeled as genetically inherited and as a dominant trait. However, the University of Utah considers dimples an "irregular" dominant trait that is probably controlled mostly by one gene but is influenced by other genes.
The truth is that dimples are actually genetic defects that are caused by shortened facial muscles.
Dimples are caused by a fault in the subcutaneous connective tissue that develops in course of the embryonic development. A variation in the structure of the facial muscle may also cause dimples.
This is an inherited trait in humans, where the dominant gene causes the cleft chin, while the recessive genotype presents without a cleft. However, it is also a classic example for variable penetrance with environmental factors or a modifier gene possibly affecting the phenotypical expression of the actual genotype.