The brain is a physical organ, and there is no reason to suppose that its growth and functioning are not controlled by the same rules of heredity and development as the rest of the body. It would not, then, be strange to find that intelligence is more markedly present in certain groups.

For example, most ethnics in the cold north are more intelligent since the harsh environments and climate made the life very difficult compared to hot tropical climate and therefore the genes with superior intellects are more likely to be selected. I thinks its obvious when you see most of high achievers in malaysia are of chinese descents. And also if you try to compare ancient european and east asian civilizations with south east asian or african(which literally non-existent), they are much more magnificient. One should always acknowledge and face them. I myself could actually live quite comfortably with the discovery that intelligence either is, or is not, mainly controlled by genes, and is sharply different between populations - even if it were shown that my own ethnic group is on the stupid side. My own intelligence would remain as it is

As for the jews, only the ashkenazi(german jews) are known for their intelligence, mainly because of their people being persecuted by the european for hundred of years, only the educated people or rich merchants with genetically higher IQ are able to survive and reproduce consistently

btw watch this
http://www.youtube.com/watch?v=BXRjmyJFzrU&feature=related