Someone summed up my previous post as “Hungarian education isn’t magic”.
But it seems more important to consider a less silly argument – that practice is one of many factors, and that enough of it can make up for a lack of the others. This study showing that amount of practice only explains 12% of the variance in skill level at various tasks, and is often summarized as “practice doesn’t matter much”.
The Polgar sisters’ IQs might have been a permissive factor in allowing them to excel, but it didn’t necessitate it. Malcolm Gladwell uses the Polgars as poster children for his famous ‘10,000 hours of practice makes you an expert at anything’ rule.
The Polgars had 50,000 hours of chess practice each by the time they were adults, presumably enough to make them quintuple-experts.
We would expect them to need much more practice to achieve a level of proficiency similar to those chess masters, and indeed that seems like what happens.
(all of this is confounded by them being women and almost all the other equally-good chess masters being men.