All of thats true Nick but I think there are far more important important factors, like when you took up the sport in the first place for example. I think I was 46 when I ran (very very very badly) my first fell race

. Also way back last century when I was at school, although I did quite enjoy cross country running for a while and do okay at it, I was mainly into team sports (football and rugby) and later after that karate and hong kong fuey, none of which particularly helped me improve at running. I suspect that now, aged fifty flipping five, I'm a far superior runner than I ever was at school or probably anytime since. Had I given running a proper crack at the time though I could have ended up being miles miles better than I am now. Peer groups when you're young and what you go for, from the wide range of interests open to you, probably dictate more than anything how you'll end up and what things you might get good or not so good at. In the scheme of things genetics are but a small fraction