Usually the result of some pituitary abnormality. But as they said, they can't figure this one out. I mean, he had all his teeth at 4 months? Usually folks with these kinds of issues do not live a long life. And it's got to be hard for him being 12 and trying to fit in.
It's tough enough being a teenager, I hope his family and friends help him deal with his amazing situation.
I'm wondering if it's just the height. His voice sounds very strange and it looks like he can't even open his eyes. Poor kid.