If your blond preteen seems to be turning into a brunette, you're not imagining things. For some children, hair that starts out platinum blond gradually becomes darker and may end up dark brown, or even black, as they grow.
So what causes this change?
The short answer is that hair color is controlled by a complex interplay of genes, pigment-producing cells and, later in childhood, hormones. Scientists understand many of the genes involved in hair color, but they are still trying to find out why some blond children's hair darkens while others' locks remain blond for life.
"It depends on their genetic inheritance," Desmond Tobin, a professor of dermatological science at University College Dublin, told Live Science in an email.
Hair gets its color from a pigment called melanin, which is produced by specialized cells called
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