Interesting poll and interesting results so far.
The hypothesis behind this seems to be that a left or right curve can be explained by the hand you masturbate with. For various reasons that have been discussed on the board, I don't think that is a cause, or at least not a determining one, and that it is essentially a question of genetics.
The responses so far are intriguing, as far more men who have a right and ('especially) a left curve than those who have no curve have answered. Yet it is certain that there are many more men with a straight erection reading the board, but who do not bother responding, because they are not concerned. You are therefore more likely to get answers from men who do have a curve and who have wondered how they got it (which is just why I answered).
Still, the responses should be interesting.