Due to genetics of course, otherwise, the way I train and eat would produce the same results across the board.[b said:Quote[/b] ]Growing more muscle is merely finding the specific formula for your body in my opinion. Of course the formula is more simple (easier) for some than others.
[b said:Quote[/b] ]And Larry Scott or a 15 year old Schwarzenegger are the examples I would refer to for genetics being minor. Larry attributed his BBing career to the fact that "I used to be one of those 98lb weaklings...", and Arnold didn't look any different from your standard 5'9-6ft high school male in my opinion. The only outstanding quality would be his tone, or lack of fat.
It's not what they looked like before weight training, it is how they respond to it that will attest to their genetic potential. Case in point, train your chest in the exact manner as Arnold did, even do the same diet and drugs, and see if your chest looks anything like his did. If not, then what explains the difference if genetics is as insignificant as is being asserted?