Yeah, mine is the same way - mine leans to the left and has a slight twist (or roll as you call it) to the left. Its normal. Most penises aren't perfectly straight - a lot of them have bends, curves, leans, twists, etc.
Mine was straight before puberty too. I have a theory as to what causes it, but its only a theory. I think that it depends on what side you usually sleep on during puberty. Most penis growth occurs during your sleep during puberty. So for example, if you usually sleep on your left side, and the growth occurs when it is hanging to the left while your sleeping, it could be growing that way, and end up with a permanent curve, lean or twist. I dunno, just a theory.
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