Hes probably just doing something that you aren't. Look at his diet/workout schedule. Sleep schedule. Try following it all and you will probably get near the same gains he does
genetics my friend. in bodybuilding you CANNOT WORRY about other people, you gotta do your thing. I'm sure you have a lot of talents he doesn't have too.
if he starts lifting at 13 and keeps it up by the time he is in his mid 20's he will have a very solid base and then he can start juicing and will be a beast by 30.
I know. It's just insane. Just the other day we were wrestling and I was shocked by how he could pick me up and move me around. And I outweigh him by 30 lbs! Which is sad, considering the 5 year age difference.