Pattern baldness is an example of sex-influenced inheritance. Sex-influenced genes are expressed in both males and females, but pattern baldness is expressed more often in males than in females. Male pattern baldness is the most frequent reason for hair loss in men. The gene acts as an autosomal dominant in males and an autosomal recessive in females. One out of every five men begin balding rapidly in their twenties. Another one out of five will always keep their hair. The others will slowly bald over time. The level of baldness is related to the quantity of testosterone in a man.