I read some articles in "Psychology Today" about how bilateral symmetry can make a person very attractive. For example, Denzel Washigton, LizTaylor, Linda Evangelista all have very symmetrical faces (they took two left sides of their faces together and two right sides, and there was hardly a difference).
http://www.psychologytoday.com/htdoc...101-000033.asp
http://www.psychologytoday.com/htdoc...101-000034.asp
Essentially, we are all asymetrical to a degree, facially and in "other" areas.