Our genes control the color of our hair, our height, the size of our feet. And genes probably influence other, far more complex traits like our immunity to certain diseases, our level of agility, and probably even our predisposition to addiction.

The importance of our genetic make-up to the person we ultimately become has been debated since long before scientists discovered DNA. The nature vs. nurture debate raises the question, Is who we are the result of the genetic material we received from our parents, or do we all begin life as relatively similar blank slates, becoming unique only in response to the particular environmental conditions we encounter as we develop? Most experts believe the answer lies somewhere in between.

While many physical traits have been clearly linked to particular sections of DNA code, human behaviors have been far more difficult to pin down. For example, explaining criminal behavior in terms of personal psychology and history is much easier than finding a gene or genes responsible for such conduct. However, a growing number of evolutionary psychologists argue that many behavioral traits, including mate preference, must surely be influenced by the genes we inherited from our ancestors -- the result of millions of years of natural selection.