I believe that Chua was talking about the Ashkenazi Jews. I was convinced of the "scientific racism" explanation for their achievement based on the evidence presented in the book the 10,000 The 10,000 Year Explosion: How Civilization Accelerated Human Evolution Paperback by Gregory Cochran and Henry Harpending. Nicholas Wade, a long time writer for the New York Times also made the same arguments in his book A Troublesome Inheritance: Genes, Race and Human History although I haven't read it.