I met Susan Polgar when she came to give a talk at the UW. She is a rather intelligent woman, though one does not get the impression that she’s a true genius.
Laszlo was a smart man. Like many fairly naive intellectuals, he downplayed the role of talent (innate ability) in success. He had three relatively bright daughters. He homeschooled them and drilled them in chess from the time they were very little. Of course they would grow up to become good chess players - even a kid with an IQ of 90 would become decent at chess if you drilled him/her really intensely from an early age (though he/she would not be nearly as good as the Polgars). But if you combine solid overall intelligence with extremely rigorous training, you’re going to get some great chess players. All three Polgar sisters are over 2400 elo. A lot of people may think that that’s not really that hard to achieve, but if you’ve ever played chess against someone who is over 2000 you know that it’s really hard to even achieve a 2000 rating.
I am actually more likely than the average person to speak of the importance of practice and hard work. But I also get really annoyed when people use examples like the Polgar sisters to suggest that there just is no such thing as innate talent.
Those who have been observing top-level chess (read: one ten thousandth of the US population, perhaps?) have been observing Magnus Carlsen reach dominance. He is now eighteen years old and rated over 2800. He is the highest-rated player in the world. He just won Nanjing with an amazing score, scored +2 at the Tal Memorial (though Kramnik won), and is now leading at the World Blitz Championship, ahead of even Anand.
Maybe it’s just me, but I think anyone who denies that someone like Magnus Carlsen (or Bobby Fischer, or Vishy Anand) was born with something that most people lack is out of his mind. While Magnus Carlsen has worked very hard, I know somebody who has studied chess just as much and is rated 600 points lower. The same sort of idea goes for many other activities. Terence Tao, Stephen Wolfram, and Barry Mazur all earned PhDs before they were 22. Hard work pays off - so does being dealt a genetic hand of four aces.
I think a variety of psychological biases and quirks combine to produce the desire to deny the existence of innate talent, but I won’t delve into them here. The source and nature of the biases depends on the person and his/her goals and personal experiences.