Hair is developed in hair follicles that are like minute pouches just under the skin surface. A hair usually sprouts and grows from each follicle for approximately three years. It’s then shed and a new hair sprouts from the follicle. This cycle of hair growth, falling out and new growth goes on. Men, due to their genetic-traits, have hair follicles that act in response to DHT (dihydrotestosterone). Gradually, DHT causes hair follicles to shrink. Eventually, the follicles shrink so much that each new hair is thinner than the preceding one leading to baldness.