[NitpickLawyer]

> No, they couldn't.

Isn't that a bit too certain for something that's not settled at all? How else would you explain the Polgar sisters? I'm sure there are other examples, but this is the most famous one.

[jonahx]

Few claims in the social sciences are more fully settled. I don't think you could find a researcher in the world at a major university making that claim that randomly selected children could be reliably turned into world-class mathematicians with enough training.

> How else would you explain the Polgar sisters?

Genetics is the obvious explanation. The father was clearly very intelligent.

Also to clarify: I agree that training and effort can have large effects, and that focusing on them is a good strategy. Over-believing in them is probably a good bias, even. But the idea that everyone is more or less the same except for effort is ridiculous.