the lack of perfect symmetry is why we don't usually like our own photos-- we are used to looking at ourselves in a mirror, and we get used to that view. in a photo, we don't have that reverse symmetry, and we don't look as we would expect.

it is very interesting to take a full frontal face view, slice it down the middle, and then make two perfectly symmetrical faces out of each half.. not to hard to do with a program like photoshop.

the three images are distictly different, and both look like the whole face, but the doubled right and the doubled left often don't look at all alike.

still, there is a good deal of evidence that the concept of beauty is linked to symmetry in the face.