That opinion is getting harder and harder to defend with studies coming fast and thick like the instant one. No matter how much the lefties don't like it, if IQ correlates to definite, measurable, objective biological differences then it is stupid to maintain it's not a real phenomenon.
What does an IQ point measure? What definite, measurable, objective biological quantity does it represent?
Synapse speed?
Neurons firing/second?
Brain current?