Genetic hertitage has to be damn important
It might be politically incorrect to say this, but genetic heritage has got to be incredibly important.
Those who are world class at anything were born with abilities the rest of us do not have (I am arrogant, but I know my limitations).
The water is muddied by the fact that a really bad environment can cripple either the mind, the body, or both. I am sure that a well designed terrible enviroment could make both Einstein and Michael Jordan into clumsy idiots.
The problem is that the converse is just not true. The mental giants and superstar athletes were born with abilities the rest of us just do not have.
Intelligence, artistic ability, and various other mental capabilities are hard to define, let alone quantify. Howeve, all the human abilities that can be defined and quantified seem to have a big genetic component.
Anybody who thinks that the right environment could have made him/her a superstar in science, art, or sports is either arrogant or stupid.
I knew a genius when I was a teenager. They are different from us, and it shows up early. Think of Mozart: He was composing & playing brilliantly when he was 6 or 7.