It isn't IQ. It is environmental culture during childhood development. If you grow up in a family that values intellectualism you will probably be intellectual, curious, logical, and skeptical. If you grow up in a family that is hostile to intellectualism, you are more likely to be ignorant and manipulated by emotional falsities as well.

The problem is more kids are growing up anti-intellectual than intellectual. IQ has nothing to do with that, intellectuals uplifted civilization from effectively universal anti-intellectualism (at least in Europe) in the 16th century to where we are now.

We have the most intellectuals ever now, but that doesn't mean we are close to a majority, and that also means as long as anti-intellectualism is prevalent you need systems of rule by minority (in various forms) to see progress happen.