Genetic endowment is a necessary but far from sufficient condition for reaching the top levels in this sport. And people speak of running "genetics" as if it were as simple a matter as eye and hair color determination-- i.e. as if there were a set of discrete genes that determined things like degree of response to training, inclination to train, or any of the other things that underlie success, which there are not. And bear in mind that even if there were such genes, every individual will also inevitably have some genetic predisposition to things that might HINDER athletic performance-- like, say, clinical depression.
Sport, like most other life pursuits, is a complexly socio-cultural affair. What is the point of talking about "genetics" all the time when we can neither isolate the genes supposedly involved (and separate their effects from those of other genes), nor separate these effects from the personal/cultural determinants of success? What would all these genetic-reductivists have everyone do, quit the sport, or refuse to coach/encourage anyone whose parents didn't make a national team? I mean, what exactly are they trying to say? What bothers them so much about the idea that someone who may not appear to be "genetically privileged" might want to do the sport seriously, and who might think they can be really good at it? The fact is, most of today's elites are not the children of elite distance runners, and many elite parents have children who demonstrate only average ability (and that's even with the environmental advantages).
Why does so much discussion on this board have to devolve into the most simple-minded ideological non-debates? For instance, you know that underlying this discussion so far is the "libtard" belief that anyone can be great if they only try hard enough, versus the "libertarian-tard" assertion that any and all observable social hierarchies are embedded in immutable natural differences. These are not the only options.