There was an interesting study done based on questionnaires given to 04 marathon trials qualifiers, men and women. They found that on average the men all did about the same mileage, some individuals in both groups were much higher or lower but overall mileage was not a good indicator of what there qualifying time would be. But they found there was a big difference between the elite women(they picked a time and said everything under it was elite) and the rest of the fields mileage.
Now I think this study is a little flawed just in that a 2:22 was a heck of a lot closer to the top men in the world then 2:47 is to the top women. In other words if they studied men who ran sub 2:30 or something they would find the same results.
If women ran more would they be better, yes. Is there a bigger injury risk with mileage, yes. You need to work around that. I tried 100 mile weeks in college got hurt, fixed the problem tried them again and got hurt, fixed the problem and its source changed how I did things and approached things differently became more careful and tried again and again. I still get hurt but I learn from each mistake and keep getting back in the game. I honestly believe most anyone can be at least a sub elite runner with enough time and persistence. I run anywhere from 130 to 170 a week now and have less injury problems then I did running 35 miles a week in high school. also I'm a "good" runner now.
Talent is almost always discovered in retrospect. I spent all of jr. high, high school and college hearing from every coach, friend and parent what a shame it was I didn't have any talent because i was such a hard worker and deserved to succeed. Now I have people tell me how lucky I am to be so talented. I love it, I smile and tell them "yes I am!" they'd never believe me anyway.