I am left wondering if the differences in brain anatomy happen because these people read more and thus become good at reading, i.e., the brain is plastic, or th

I am left wondering if the differences in brain anatomy happen because these people read more and thus become good at reading, i.e., the brain is plastic, or these people have a proclivity to be better at reading because their brain is structured differently. Unless I missed it, there isn’t much mentioned on plasticity in the original paper.