Extremely symmetrical men are less attentive to their partners and more likely to cheat on them. Women show no such tendency. Our innate tendency to prefer symmetry unfortunately doesn't prepare us to prefer integrity, personal worth, or life in complex technological societies. One genetic characteristic that symmetry reveals is genetic diversity. The ability to successfully resist or withstand various environmental traumas or parasitic infection.
Pathogens are least resistant to rare alleles.
A specific type of asymmetry called fluctuating asymmetry is observed in teeth. It just means that teeth are larger on one side than the other. A biologically strong individual, whether a rat or human can better withstand stress than a weak one. Fluctuating asymmetry correlates with lower survival and growth rates, and fewer offspring. In art and architecture is a legendary old proportion known variously as the golden proportion, golden section, or as Fibonnaci Numbers.