I'm 25, and as far back as I can remember, I've had two-toned skin on both of my legs. I'm not talking about splotches or tan lines. I mean that on the insides of my legs, running from my knees down to ankles, I have a rather obvious line that separates light and dark skin. The skin gradually turns from light olive to tanned olive skin as it wraps around my leg--with the two ends meeting up like a seam running down the insides of my legs. The smooth color change thankfully isn't noticeable unless you see the seam. I've got seven siblings; I've asked them all, and none of them have this issue. Does anyone else have this going on? I mean, it seems like a rather strange birthmark.... (I would post a pic of it, but I can't seem to get it to photograph well.) Has anyone else heard of this? I'd love any ideas or opinions on what it might be. Thanks!