If all sport were purely based on individual merit, then of course genetic ability would be a big factor; in some cases it is, there are some exceptional athletes succeeding out there who've worked very hard to achieve incredible things.
But it is far from the only factor, especially where politics and financial backing are important. This is very true in racing, and in cycling. What is your last name may be the difference between getting chosen for a seat, or not. It doesn't mean the person is not qualified, or didn't work as hard. But if two guys go around the F1 track at the same rate (or within a few hundredths of a second) and one brings millions of euros of funding... well, the choice is made, isn't it? Lance Stroll (F1) is a very talented driver, but certainly gets a lot of help from his billionaire father.
Add in that if your mom and dad can teach you things from a young age and put you literally years in front of your competitors as far as practice and training goes... you're not genetically superior, you've simply got the benefit of experience that others haven't had, and that might make you a better competitor. Or maybe they can put you in contact with the right coaches, sponsors, systems, teams, funding sources... again with F1, I think of Rosberg (Nico; dad Kiki), or with cycling, Roche (Nicolas; dad Stephen).
As is often the case with this sort of question, its "a bit of both", but depends very much on the structure of the sport.