This is an inherited trait in humans, where the dominant gene causes the cleft Chin.

http://en.wikipedia.org/wiki/Cleft_chin

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. Cleft chins are common among people originating from Europe.