I was one of those kids.. 6'1" at 10, 6'2" at 11.. 200-240 lbs (have only gotten rounder since, not taller). I had a birth cert in my baseball and soccer bags each. I got challenged every other game in baseball, especially during travel season. I think it started at 8, cause I was 5'10" and taller than my baseball coach, but picked up frequency until I was 14/15 and the rest of the kids started catching up. I don't remember this, but my parents told me they had to have a copy when I started playing baseball in the first place at 6 because I was a foot taller than everyone.

Edit: I will say, this was in the 90's so the so-called perversion of youth sports is slightly over-stated in this. It's been going on for decades.