genetics is #1. period. doesn't matter how much you pump yourself with drugs if the next guy responds like a freak to half the dosage. i've known dudes using a gram of test just as the base and they look like tomato-headed idiots, meanwhile the next guy over tries a mini-cycle and blows up.
the difference between a natural and an enhanced athlete is obviously 100% drugs, but the difference between ronnie coleman and dave palumbo is genetics. everyone's doing the same shit, using the same shit, sticking with mostly the same trainers and "nutritionists". if it was just who used the most gear i'm pretty sure greg kovacs would have set the olympia record.
and don't get retarded, if arnie and sergio had access to what's around today they'd have looked like today's bodybuilders. franco would be branch, arnie would be gunter or dennis wolf, sergio would be ronnie.