From article:

Facial symmetry is sexy, but perhaps not for the reasons scientists had long thought.

If people aren’t attracted to symmetry because it provides useful information about the value of a potential mate, why do humans find symmetry so sexy?

One possibility, Pound said, is that people simply like symmetry in all things, from art to natural objects to faces.

Read more:

http://www.livescience.com/47322-facial-symmetry-sexy-health.html