Evidence on the presence and history of assortative mating

"Six of the nine traits, including educational attainment, showed greater genetic variance among offspring, which is inconsistent with stable assortative mating over many generations."

Ok... maybe I'm not understanding. I don't think educational attainment is inconsistent with assortative mating. In fact, I think it is consistent with the theory as it applies to passing on traits. The theory only really applies to traits with high genetic influence (for passing on). Educational attainment is not genetic. Even if it's partially associated with IQ (not really), IQ is not all that strong of a heretical trait.