There are, however, also credible voices that point out that genes play a rather significant role. Cynthia Kenyon (professor at UCSF), for instance, argues that the aging process, like everything else in biology, is under exquisite regulation. In fact, experiments with roundworms and mice have shown that the manipulation of a single specific gene can already increase life expectancy by up to 600%. I have briefly written about this topic in an older entry of my blog: http://takeoffphenomenon.blogspot.com/2006/03/surviving-longer.html

Best wishes
Thomas