I think that parenting/coaching has less of an effect at this stage than natural talent and tactical "eye". There are not many Polgar families are out there and you can not really name a single chess champion/prodigy dynasty either. This is suprising since genetics seems to have impact in so many other skills: music, science, medicine, sports...Chess is unique and it is quite puzzling what skill set propels certain kids to grandmaster level so quickly.
Why Junior Grandmaster?

My question then is this: how could Fischer run up against the USSR? There is no doubt there were thousands (or more) of chess trainees there with plenty of training, early on I might add. Fischer himself was mostly self taught, an extremely hard worker himself, no doubt. But you here see a combination of talent and extremely hard work (capable of which also takes talent, see Botvinnik).

I think that parenting/coaching has less of an effect at this stage than natural talent and tactical "eye". There are not many Polgar families are out there and you can not really name a single chess champion/prodigy dynasty either. This is suprising since genetics seems to have impact in so many other skills: music, science, medicine, sports...Chess is unique and it is quite puzzling what skill set propels certain kids to grandmaster level so quickly.
The Polgars are themselves a very strong argument by the "nurture" camp against the "genetics" camp.

I would think the Polgars' success suggests that nature and nurture are intertwined. The father wasn't untalented at chess.

Do you know any other family like the Polgars? Laszlo wrote a book "Bring Up a Genius" or something like that. This book did not result in an explosion of chess dynasties. That is for the family idea...
"(Polgar )László could be beaten by his daughter, Judit, when she was just five..."
http://www.supermemo.com/articles/genius.htm#Genius%20in%20chess
The answer here is that it takes talent AND nurturing, although, once again, you do not find that most world champions or prodigies had that much of the latter. Capablanca, Reshevsky, Alekhine, Rubinstein, etc. You show talent, THEN the teacher appears...(Waitzkin-Pandolfini, Carlsen-Kasparov)

I think that anyone with average intelligence can become a GM if he has enough ambition, time, and resources to apply to it.
Why not, if they begin working 4 hours a day when they are a 6 year old kid and increase that up to 10 hours a day as an adult.

So, what do you actually study for 10 steady hours a day? I mean this sounds like a stairway to madness or at least a mild stroke...Then again, you must be living at home, while momma is downstairs just busy cooking them pork shanks...

So, what do you actually study for 10 steady hours a day? I mean this sounds like a stairway to madness or at least a mild stroke...Then again, you must be living at home, while momma is downstairs just busy cooking them pork shanks...
8~10 hours is the average working hours for any active top GM. I don't really know about the "average" active GMs, but I would be very surprised if it's below 8 hours.
Kramnik and Anand have worked 12 hours/day in their 6 month preparations to WC matches.
I just wondering, why some kids become Grandmaster in very early stage than the others. It is because they are gifted, proper chess lesson from their parents, or their brain work well in calculating and understanding part of the chess game or combination of possibility mentioned?
It is experience in chess game something that is not compulsory to play against experience people as most of these kids definitely have less experience than the adult player.