More exposure to upper middle-class culture increases ones ability to take IQ tests.
I don't think golf and tennis increases IQ
He's saying that low-class culture does not include quality education or quality influencers. Note that I'm not using influencer in the traditional sense here; I'm referring to anyone - dads, friends, acquaintances - who influences the child.
Gluten reduces IQ (jk)
Lots of good reason to believe nutrition does.