It used to be thought that fiber type was what you were born with, but we show that's not the case -- training has a huge influence.
Genders/sexes aside, I don't see how their study proves this point. If I understand it correctly, they only looked at 12 world-class athletes. As far as I know, genetic preconditions play a major role in becoming world-class in more or less any sport. So if you're looking at the very best athletes of the planet, chances are high, you're also looking at people with the best (or at least very good) genetics.
Getting a world-class weight lifter, marathon runner, basketball player etc. is not achievable with the right training and food only.