It's 98% how bad you want it, 1% genetics and 1% environment.
In HS I was probably not as talented as my teammates, but wound up running faster. I used to go home and work out more after practice, run on the weekends. I did all the small things like, eat right, take vitamins, stretch etc. Keynans work so much harder that other people. They have tougher lives, so of course they are stronger and cant withstand the pain of training and racing. Same with Ethiopian people etc. Americans have become fat and lazy, they just don't know how to push it anymore.
I ran 9:54 3200m in HS, none of my teammates broke 10:00min. I was district champ, ran my last 400 in 66. I know its not that fast, but if I continued after HS I would have been able to run with the best based on my training philosphy