Heritable and experience-dependent cortical traits of reading ability.

Reading ability emerges from interacting phonological and semantic skills. However, the cortical microstructure supporting these traits remains unclear. Multimodal cortical parcellation and diffusion analysis were performed in 1,068 participants, including a genetically informed twin subsample. We identified auditory and anterior temporal subregions predicting oral reading scores. In the left auditory cortex, myelin in a paralemniscal (belt) area was heritably linked to reading, whereas thickness in the lemniscal (core) region reflected experience-dependent contributions. Bilateral anterior temporal lobe (ATL) surface areas were genetically associated with reading and predicted semantic performance, providing novel cortical evidence for heritable semantic substrates of literacy. The left inferior fronto-occipital fasciculus and a left ATL region connected with the arcuate fasciculus predicted reading scores independent of genetic influences. The cortical traits were linked to reading continuously across the population, challenging categorical models of dyslexia. The findings suggest that genetic and experience-dependent mechanisms jointly shape the phonological and semantic foundations of literacy.