In the course of a lifetime, the activity of the melanocytes in each follicle begins to wane, resulting in gray hairs. Each individual's melanocyte-clock is different, but in Caucasians this reduction of melanocyte activity usually occurs earlier than in other groups. The appearance of gray hairs may be the result of a child's genetically determined maturational schedule. If these others had scattered gray hairs in childhood, but did not progress to a full head of gray hair until later, then it is likely that your son would follow the same pattern. Gray hair can also accompany a number of uncommon familial syndromes, including neurofibromatosis and tuberous sclerosis.
Several conditions can alter a child's preset melanocyte-clock.
The most common of these is vitamin B12 deficiency. Vitamin B12, or cobalamin, is present widely in foods from animal sources. Dietary deficiency is difficult to achieve, unless a person is eating a strict vegan diet. Breast-fed infants whose mothers have B12 deficiency can also develop a transient deficiency. A lack of vitamin B12 can occur even in the face of adequate B12 intake.