What about all the people who say "anyone can be a pro/cat1, there is no such thing as genetic limitations only lack of training discipline"?
They are lying, or trying to sell you something. I guess we need to find a few sets of twins. And talk half into the favored scientific training method of the day, half into JRA and see what happens.
Grumpy, If the goal is winning and placing in Races (hence the term Bike Racing). Then Category upgrades, since they are based on results, are I would think a reasonable measure.