Beverly Clydesdale, age 13, of Langley, British Columbia, Canada, for her question:

WHY DOES HAIR TURN GRAY?

The color of your hair comes from a pigment called melanin which is deposited in your hair cells as they form in the root. Melanin can produce hair colors that range all the way from black to blonde.

As a person grows older, the pigment melanin often is no longer deposited in the newly forming hair cells. The hair then gradually becomes gray or white. This condition happens at an early age with some people, and doesn't happen at all with others. That's why you'll find some youthful people with gray hair, and also some very old people without gray.

Pigment is deposited in the hair before it grows out of the skin. For this very important reason it is impossible for a person's hair to turn gray overnight