From Robert Gonzalez in io9:
You know what I'm talking about. There you are, clicking through your friend's Facebook album, when suddenly you happen upon a picture of yourself — or rather, a slightly less attractive version of yourself. The “real” you appears to have been abducted, replaced with some second-rate knock off. What gives? you ask yourself. Is that really what I look like?
Yes. Yes it is. But don't worry, there's a perfectly sound explanation for why the person staring back at you looks so very unfamiliar, even though that person is, well, you. And by the way: that funny-looking, ersatz-you in the photograph? They're actually more attractive than you think.