Genetically sensitive hair follicles shrink when exposed to DHT. As the follicles become smaller, the hair growing Anagen phase shortens and the resting Catagen and Telogen phases lengthen. The hair becomes increasingly thinner, shorter and less deeply rooted. Eventually, hair growth stops.

While it is still not known exactly why hair loss occurs among certain people, researchers have noted a greater incidence among various racial and ethnic groups. Caucasians, for example, are more likely to lose their hair than Asians. Current evidence suggests that the genetic predisposition can be passed down equally from both the mother and the father's side of the family.