Although it’s not completely understood, men go bald on their heads but not their bodies thanks to a hormone called dihydrotestosterone (DHT), which is a derivative of testosterone. Up to 10 percent of the body’s testosterone is converted into DHT starting from when a boy hits puberty. Both contribute to male sex characteristics, such as a deep voice and muscle mass growth.While hair follicles on the legs, back, and other areas require the hormone to grow, DHT essentially causes hair follicles on top of the head to shrink and shut down prematurely. Genetics plays a large part in how likely a man is to experience this type of hair loss.