Mine did about two years ago. Mom was very concerned if this boy was going to be 'prematurely' aging. I am sure that the grey hair at such a young age is caused by certain mineral deficiencies.
So, Mom googled and discovered that grey hair is caused by zinc deficiency. And thankfully I still had some a bottle of Nutrilite zinc magnesium supplement in the fridge. I had bought a bottle or two of health supplement including Vitamin C for the kids but as they grow older, they seem to be choosy and refuse to chew the not-so-appealing supplement.
For a few months, Mom diligently fed Wyng with regular doses of zinc magnesium. Not wanting to be overly confident, I did notice the less visibility of grey hand on his head. In fact, after a few more months, the unsightly grey hair are all gone.
Now, after almost 2 years, he has a headful of dark hair. Thanks to the zinc supplement.