Genes or Lifestyle Choices?

I recently ran at the Syracuse Festival of Races 5K on October 2, 2011. I was surprised to see some of the great running times of people in their 50s, 60s, 70s, and even 80s! Often times, people complain that they are too old to do something and say things like, "Well, when you get to be my age, you won't be doing those things." Or "These old bones can't do what they used to." I guess my question is, are these people running such great times because of excellent genes or plain old hard work and active lifestyle choices? I suppose it could be a combination of both, but I'm hoping for the latter because I do not believe I'm blessed with good running genes. Take a look at some of the ages and times below and please comment on what you think to be the case.