Man this kid is not on steroids, its just genetics. Some of you guys make me laugh.
He has great genetics for size. However, this is not "6'5" 250lbs of solid muscle". I'm 6'5" and 235lbs right now, and if he stood beside me, I'd make him look like exactly what he is... a kid.
This is not to take anything away from him, way better genetics than mine, and he is huge for his age.
He is exactly like my younger brother. While he is maybe 1/2" taller than me, we are built totally different.
When I was like 16, I was 6'4 or maybe 6'5 already, and weighed a whopping 165lbs. My brother by the time he was 14 was walking around 225lbs+.
I've been training legs for years and right now I think my quads are around 27" (might be 28", I forget because it doesn't matter, they still look like sticks). My brother on the other hand, I don't think has squatted in his life and had close to 30" quads in high school. He is naturally broad, and has what I call "a farm boy built". My dad uses to call me Stick, and him Log
Even now, he still doesn't lift, and he is around 340lbs (fat, but thick). I stuff myself with 6000 calories a day, and can't break 265lbs.
And even at 340lbs, he still plays basketball weekly in a men's league (with some national level guys/ ex pros) and can still dunk. Myself, I look like I should be able to (meaning look way more athletic), but if I'd go up for a dunk, I'd throw my back out and be crippled for a month.
So, I've seen it with my own eyes, I grew up with it, certain people are just big. No steroids required. Not even training or a lot of calories, they just grow.
I know there will always be some crazy kids that juice up at 13 or 14, but thats not always the case.
The fitness community has a hard time believing that someone's genetics can make them much bigger than average, yet they have no issue seeing a 7'2" guy and admit that his height is due to genetics.