I think it might be more common to be missing limbs than to have extra ones... Unless you count extra fingers/toes as limbs. Not sure how common those are either.
It's very uncommon, so this is a... nice, normal thread.
Seriously though, if your mother was living beside the Springfield Nuclear Power Plant whilst pregnant then please send photos of your third eye or whatever! And don't be offended...
It doesn't count as a limb, but I was out with some of my upperclassmen friends once and we were talking about random stuff, which led to one of the guys blurting out 'I have an extra toe!' We didn't believe him until he pulled his left shoe and sock off. I didn't think an extra toe was that weird, but he only had one extra toe on his left foot and not his right, and that was the weird part for me. Asymmetry bugs me.
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