I think I can probably only do about 20% over my bw for 3reps...I've only done 110 for 3reps hang pc.
Some kids are freaks. My mate went to school with a guy that was about 5'8 and he could dunk when he was 16. No build, no nothing, but crazy mofo hops! He's wasted and he's done f0ck all with his athletic ability. Last I heard from my mate he was a fat slob now that he's over 30. But back in his day he was the freaky 5'8 kid who could dunk!
Little bro is a freak, but he's trained for 5yrs now so it wasn't gifted to him. He had a knack for flexibility and he's learnt the lifts very well but he had no real natural freakish strength or anything. He just worked hard and got strong (2x bw back squat) training.