sorry i must write in english, no hebrew on this keyboard.

no it's not becuse they invest more hours now.

in the case of the polgar family, the father decided to make a project out of his daughters, he spent practically all his free time on teaching them chess , buying lots of books on the subject and hiring tutors, the father himself is a poor player but he figured that since he and his wife are intelligent people they should have intelligent children and since chess is about a way of thinking , he could make chess champions out of his children.

the father of the williams sister realized something similar: since both he and his wife are fairly athletic and since blacks are generally more athletic than whites, if he trained his daughters to play tennis at a professional level, they would have a very good chance of reaching the top, since tennis is usually played be people from well to do neighbourhoods.

chess and physics are quite different, it's much easier to teach chess because it's a game and children love playing and beating their opponent.
also, you need to learn much more for physics and i don't think many children will gain access to a particle accelerator

about the polgar household
http://www.telegraph.co.uk/health/3294892/Queen-take...
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however there is a distinct possibility that you can make a child a genius in advanced sciences , someone already mentioned sidis and he is an example of what can be achieved and of the costs...

if Mr williams had "taught" his daughters golf there is a good chance that they would have become very successful golf players, tiger woods was engineered too as you can see.
http://www.youtube.com/watch?v=_wHkA_983_s

however, since golf does not involve much running and jumping it would have been a wrong move on his part as he would be giving up the racial advantages.

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http://www.gate2home.com/?language=he&sec=2

GREAT keyboard!