White or Gray hairs are the results of hair that lacks melanin, the pigment that gives hair its color. Without it, hair is transparent but looks white because of the way light is reflected off it.
As we age, our body naturally produces less and less melanin until eventually hair turns white. If your family has a history of white or gray hair, it is likely that you will inherit it as well. Vitamin deficiencies, gland abnormalities and excessive stress of anxiety may also cause premature graying