Okay, this may have been mentioned before in this long-ass thread, but I'm going for it anyway.
First off, I have responded to Happeh's other thread about his theory. I mentioned the fact that my right leg is shorter than my left and I've leaned towards my right side way before I even started masturbating with my right hand.
Second, do you ever wonder if people just lean towards their dominant side. I mean, even if they don't masturbate, their dominant side will get stronger from using it to write all the time, or hold something (like a phone), or to wipe their ass...
Muscle is heavier than fat you know. Perhaps the only people that don't masturbate, according to Happeh, are people who are ambidextrous.