The article does try to control for this via the education levels of the parents: > Our results showed that reading for pleasure in early childhood can be bene

The article does try to control for this via the education levels of the parents: > Our results showed that reading for pleasure in early childhood can be beneficial regardless of socioeconomic status. It may also be helpful regardless of the children’s initial intelligence level. That’s because the effect didn’t depend on how many years of education the children’s parents had had – which is our best measure for very young children’s intelligence (IQ is partially heritable).