genetics factor into also.. i have always used slow and tight form.. i am now 44.. my knees are gone.. bone on bone.. my shoulders pop and snap.. my neck ect ect.. so one can say that it is about working the muscle.. and it is.. but even some of us who practiced great form will suffer after 25 years of it..
You are right, genetics are probably a factor, but how much is something no one can determine. I am the first to admit I don't have great genetics, both parents were not the least bit athletic. What I do have is patience, I will spend four or five sets warming up, slowly increasing the weight as I go up. When I do squats I will be twenty minutes in the rack before my first work set. I think this goes a long way to longevity.
I can't tell you how many times I've seen some kid go to the squat rack and start with three plates and do some half reps and walk away, makes you shake your head.
