Children born with a certain color may find that it gradually darkens as they grow. Many blond, strawberry blond, light brown, or red haired infants experience this.
A change in hair color typically occurs naturally as people age, usually turning their hair to gray and then white. More than 40 percent of Americans have some gray hair by age 40, but white hairs can appear as early as childhood. The age at which graying begins seems to be almost entirely based on genetics. Sometimes people are born with gray hair because they inherit the trait genetically. Some people use hair dye to disguise the amount of gray in their hair.
Two genes appear to be responsible for the process of graying, Bcl2 and Bcl-w. The change in hair color is caused when melanin ceases to be produced in the hair root and new hairs grow in without pigment. The stem cells at the base of hair follicles are responsible for producing melanocytes, the cells that produce and store pigment in hair and skin. The death of the melanocyte stem cells causes the onset of graying.