Let's take the extreme racial focus out of this first;
A better question is WHAT MAKES a good distance runner
First of all its muscular and bone endurance, obviously
Secondly its very long term training and repeated runs at longer distances
Third, and often this is a function of second, its a very efficient cardiovascular system, and even more important, digestive and metabolic system
Now
worldwide, the countries that allow or empower women to do #2 and thus get #3, are NOT the same countries that men tend to do so. This could be a source of answer.
This is simply theory, but I believe it is more about environment and conditioning trends, than race. North merican women for example, tend to be more muscular and better sprinters, than long distance.