pics. Here's what you learn. Kids can be tall like this pic of this young man, or short, but unlike stature, one item of kids that seems to generally grow at the same pace, regardless of height, are their teeth. I'd bet the farm, based on the teeth he has in that pic, that he's well a click or two north of 12 years old. There can always be an exception, but it's a pretty hard and fast rule.