1. Strength doesn't come out of no where, they are probably more active than you think, strength doesn't only come from the gym. Why professionals use the gym is to get that last bit of competitive edge.
2. I may be baised but a lot of thing i have been called talented at was hardwork and that grinds my gears quite a bit to discredit the hardwork.

There was also a comment about how some people have a higher "base" vert which is true in the regard of that each person is built different, but getting huge difference like this guy's hops requires strength built up over time. Maybe it is even that their childhood was more active or what ever else but not some magical gene "that makes you hop"