So, since you're hinting that they do, indeed, tend to lack "something" and that you know what that something is, would you mind enlightening the rest of us?

Edit: Never mind, I tracked it down:

Ashkenazi Jews have an unusual ability profile as well as higher than average IQ. They have high verbal and mathematical scores, while their visuospatial abilities are typically somewhat lower, by about one half a standard deviation, than the European average (Levinson, 1977; Levinson and Block, 1977). Han Eysenck (Eysenck, 1995) noted “The correlation between verbal and performance tests is about 0.77 in the general population, but only 0.31 among Jewish children. Differences of 10-20 points have been found in samples of Jewish children; there is no other group that shows anything like this size difference.” The Ashkenazi pattern of success is what one would expect from this ability distribution-great success in mathematics and literature, more typical results in representational painting, sculpture, and architecture.