Over 60% of men and 50% of women will experience some degree of hair loss in their lifetime. Male pattern hair loss is primarily influenced by heredity, and is caused by the effect of dihydrotestosterone (DHT) on the scalp hair of genetically predisposed men. It's effect on the hair growth cycle results in hair miniaturization. The hair shafts become finer, shorter, and eventually hair growth ceases completely. Visually this is perceived as a gradual thinning, until baldness occurs.

Hair Loss Classification Chart

Male pattern hair loss generally follows a specific pattern, but even in the most extensive cases a horseshoe-shaped fringe of hair remains. It is the hair in the donor fringe area that provides the foundation for surgical hair restoration. These hairs, when transplanted into thinning or balding areas, will take root and grow, and continue to grow for the remainder of a person's life.

Popular Misconceptions
Daily stress will not typically cause hair loss; however, traumatic events, extremely stressful experiences, or even crash diets have been linked to hair loss. Hair loss due to stress is most likely to occur if you have a condition called alopecia areata, which results in small patches of hair loss—not the traditional male pattern hair loss.

For many years it was believed that hair loss was always inherited from the mother's father. While baldness is inherited, there is no single dominant gene that causes hair loss—it is a combination of genes passed on from either your mother or father's side of the family.

Baldness genes can skip generations and are random in terms of which siblings they will affect. The more hair loss that exists in your family, the more likely the chance that you too will experience thinning hair. Your first-degree relatives — father, uncles, and brothers — will be your best predictor for future hair loss.