I have birth marks in a couple of places, I have always had them so they are normal to me, if I was to see mine on someone else I would think that was abnormal, but only because they are mine and that is normal.
I have seen other peoples birthmarks and they look quite normal on them, though I am sure if they were on me I would freak about how abnormal they are.
I have a little brown bump under my right breast. For a long time I thought it was a birthmark, but then a doctor had to ruin it for me....and I got labled a freak. She even called in some other people to show it off. It is really a third nipple. It is very small and not visible because of it's location. It is not funcuntional and there are no extra nerve endings in it. The doctor did tell me that some times these extra nipples can be functional, but thankfully mine is not.
This is also apparently hereditary...my youngest son has two extras, but his are so faint you can hardly even see them. His look like slightly darker spots that are actually slightly indented.
Well I think I'll go back to pretending that it is a birthmark now.....