Like any sport, you’re looking at about 1/10 of 1% of the population who are even born with the athletic ability to compete. You don’t necessarily need to have inherited the genes from a parent or grandparent (for every Matthieu vdPoel or Dan Martin or Taylor Phinney with top level pro cyclists on both sides of the family, there are ten pros who have no family background in any sport at all), but if you don’t have lungs that can pull in enough air, or red blood cells that can carry enough o2, or muscles that can use that o2 and some glucose to turn pedals around, and then the hand-eye l-body coordination to steer a bike at high speeds, you’re not going to make it. Because no matter how hard the 95-percentile rider works at ALL of those things, there’s a 1-percentile rider who is working as hard or harder. And that 1-percentile rider will always have the edge.