I think this is a question of what your definition of "a lot" is. If you use percentage - for example, 1% of parents, of maybe even less - 0.01%, 0.01%*7.7 billion = about a million people.
Does percentage make more sense here or absolute number? It depends on your context. I would say in this argument, it seems more certain that Von Neumann's success, which is always a function of both nature and nurture, can probably be attributed more to nature. Or, perhaps most likely, it's a rare event of talent meets incredible luck.
Just as thousands upon thousands other people, that fail to become geniuses. So that’s more like a small semi-necessary part, not at all close to sufficient, which welcomes some awe.
Does percentage make more sense here or absolute number? It depends on your context. I would say in this argument, it seems more certain that Von Neumann's success, which is always a function of both nature and nurture, can probably be attributed more to nature. Or, perhaps most likely, it's a rare event of talent meets incredible luck.