[alexandercrohde]

You're taking that way out of context. He's not saying that the left denies IQ differences between the sexes, and it's sloppy to quote half a sentence. If you read that section, he's analyzing the psychology of the left and the right.

The full sentence, which you clipped is: Just as some on the Right deny science that runs counter to the “God > humans > environment” hierarchy (e.g., evolution and climate change), the Left tends to deny science concerning biological differences between people (e.g., IQ8 and sex differences).

That is, that the left likes to pretend there are no IQ differences (between any two groups), nor that there are any psychology differences between the sexes [because it undermines their ideology, just as global warming undermines conservative ideology].

Though this may seem ambiguous, it's clear if you consider his footnote. [8]