You have noticed, with great surprise, that your teenage daughter has a few gray hairs. This could mean absolutely nothing other than she is genetically predisposed to go gray early, or it could be the result of a medical condition.
It has been suggested by Dr. Desmond Tobin, a cell biology professor at the University of Bradford in England, that hair follicles contain a melanogenetic clock that stops or slows down melanocyte (pigment) activity, which explains why human hair turns gray.
It's Different for Different People
Dr. Tobin explains that loss of hair pigmentation, resulting in what is actually transparent hair, although we refer to it as gray or white, is determined primarily by genetics and by our age. For some people, it starts early on, perhaps even before the teen years, whereas with other individuals, it happens later in life. Some people turn gray or white rapidly, while others do so more gradually. The loss of pigmentation can occur at different rates in different hair follicles.
As Early as 8 Years-Old
According to Diagnose-me.com, children as young as 8 years old have been known to have gray hair; however, this probably indicates nothing other than this particular person's propensity to gray early, which is determined, as noted above, by genetics.
Dr. Greene of Drgreene.com points out that there are conditions that can make a child's hair go gray, including neurofibromatosis, also known as Recklinghausen disease. This is a genetic disorder of the nervous system that results in benign tumors developing on nerves. A rare disease called called Vogt-Koyanagi syndrome may strike a child following a viral illness. As the child's body fights the virus, antibodies are created that destroy melanocytes, which create the pigment in our hair.
A Vitamin B deficiency can cause a child's hair to turn gray, as can megaloblastic anemia. Hyperthyroidism, which reduces melanocyte activity, can be responsible for turning a child's hair gray or white. The skin disorder vitiligo can also result in loss of hair pigmentation.
By 50, You're Most Likely to Be ...
A Caucasian person is considered to be graying prematurely if he develops gray hair before his late teens. A person of Asian or African descent is considered to be graying prematurely if he gets gray hair before the age of 30. Most of the people in the United States and Europe are 50 percent gray by the time they are age 50.