not quite correct w.r.t. the last two world wars..
In America we have the impression today that many Jewish-Americans are pretty smart. They are doctors, lawyers, mass media and political puppet masters. That's because the Einsteins tended to get away. It was more of the slum dwellers that didn't fare so well. Likely evidence exists of a slight but measurable IQ boost among the surviving Jews compared to those alive before WWII. Jewish persecution driven by envy has been going on many thousands of years and today Jews disproportionately win Nobel science prizes. From a genetics standpoint WWII possibly precipitated the biggest measurable advance in human intelligence in 100 years.