What the good Doctor noted was a fact, carefully measured by standard testing, I would assume IQ testing.
The article gave me a strong sense of deja vu, this exact conclusion was reached in a similar study conducted in the late 60's or early 70's. With exactly the same reaction from our "Politically Correct" society. The Social Scientist who had the audacity to utter such heresy was branded with the "R" word (racist), was buried in heaps of scorn and ignored hence. (Probably didn't do much for his/her subsequent academic career either. Not to menton an assault on the concept of "free speech".)
Clear case of "killing the messenger". The message remains, however.
The standard IQ test, I believe it is called the Sanford-Binet test, IS culturally biased. In the case of the US it is biased toward the dominent group, Anglo-Saxon Whites with English as the primary language construct. The test results are then matched to the testee's age for the final reading of the "IQ". In general, then, a person's IQ changes as a function of time. If one tested, say fifteen years apart over a lifetime, one would see some change in the resultant score. (I, for instance, had an eight point spread over a 34 year period of time) The ball park stayed the same, but the distance to the fence varies.
So, we can surmise"
1) IQ is a function of time.
2) As mentioned earlier, IQ is, in part, a function of cultural bias.
3) IQ is, in part, a result of schooling conditions and the effort the student makes to learn, regardless of conditions. (i.e. Orientals tend to work harder, their culture seems to revere education like a Religion.)
4) IQ is a function of the grasp the testee has of the English language.
5) IQ MAY be a function of genetics, but it is difficult to pin down. (My parents were "uneducated". i.e. no college, but very intelligent.), All four of their offspring did well in college. They also encouraged education, so it becomes tainted by enviornmental factors in the home. (Back to #3.)
So, while a study might show a statistically significant difference in IQ between certain groups, the cause/effect trail is hard to trace. More than likely a mix of all the above points. "Controlling" a group study for all those factors would be well neigh impossible.
Since Billions have been spent on Education over the last 40 years, and we don't seem to going anywhere positive with that expenditure, and that recent studies seem to indicate that Americans in general are reluctant to go into the Sciences or Mathamatics (in comparison to the 60's, let's say.)
I think the best we can do to enhance educational factors of IQ, is to encourage education and to motivate the students. It's OK to be a "geek"!
I leave it to the educators to come up with the constructs to "make it happen".