"When European immigrant groups in the United States scored below the national average on mental tests, they scored lowest on the abstract parts of those tests. So did white mountaineer children in the United States tested back in the early 1930s... Strangely, Herrnstein and Murray refer to "folklore" that "Jews and other immigrant groups were thought to be below average in intelligence." It was neither folklore nor anything as subjective as thoughts. It was based on hard data, as hard as any data in The Bell Curve. These groups repeatedly tested below average on the mental tests of the World War I era, both in the army and in civilian life. For Jews, it is clear that later tests showed radically different results--during an era when there was very little intermarriage to change the genetic makeup of American Jews."
--Thomas Sowell
I'm not usually one to go around quoting people to make my arguments for me, but if Thomas Sowell is taking swipes at it, and it is a reasonable concern he brings up, I think that says something signficant.
This book is made of fail, and conservatives ought to have nothing to do with it, IMHO.