Reading is a complex skill that relies on a combination of innate genetic traits and physical brain changes driven by practice. Recent research provides evidence that our foundational ability to process sounds and meaning is strongly inherited, while the brain connections that stitch these skills together are sculpted by reading experience. These insights, published in Cerebral Cortex, suggest that differences in reading ability across the general population exist on a continuous spectrum of brain anatomy.
Learning to read involves teaching the brain to link written symbols to spoken language and concepts. This process generally relies on two complementary networks. The phonological route maps written letters to speech sounds, a task heavily dependent on the auditory cortex. The auditory cortex is a brain region located on the upper sides of the temporal lobes, just above the ears, and is responsible for processing sound.
The semantic route maps whole words directly to their meanings. This pathway leans on the anterior temporal lobes, which are structures located near the front tips of the temporal lobes that act as hubs for organizing semantic knowledge and recognizing objects.
Connecting these gray matter areas are white matter tracts, which serve as the brain’s information highways. The arcuate fasciculus is a bundle of nerve fibers that connects sound-processing areas to speech-production areas. The inferior fronto-occipital fasciculus bridges visual regions at the back of the brain to language and meaning hubs in the front.
Past studies have often looked at structural differences in these regions to understand conditions like dyslexia. For instance, a 2026 review highlighted that about half of the variation in language and reading outcomes in children is driven by genetics, but that environmental exposure heavily influences how those skills develop. However, researchers have primarily focused on broad anatomical measures or distinct clinical diagnoses. By looking closer at the micro-level structure of specific functional zones within the auditory cortex and anterior temporal lobes, scientists can better understand how neurodevelopmental variation shapes reading ability in the wider population.
“It fascinates me how the brain’s microstructure reflects individual skills and how it builds complex networks of information,” said study author Mikael Roll, a professor at the Centre for Languages and Literature at Lund University. “I wanted to understand which aspects of this structural ‘hardware’ are partly inherited and which may be more strongly shaped by experience.”
Roll told PsyPost that reading is an especially useful model for this question. “Reading is particularly intriguing because it is a relatively recent cultural invention that requires the brain to bring together sounds, visual forms, and meaning,” he explained.
To investigate this, the research analyzed brain imaging and behavioral data from 1,068 young adults who participated in the Human Connectome Project. The participants, aged 22 to 37, were typical readers without severe clinical impairments. To separate genetic influences from environmental ones, the sample included a subgroup of 396 twins. The researchers used high-resolution magnetic resonance imaging to measure cortical surface area, cortical thickness, and a specific image ratio called T1w/T2w, which serves as an indicator of myelin content.
Myelin is the protective sheath around nerve fibers that helps signals travel faster. Participants completed a standardized oral reading recognition test that evaluated their ability to pronounce letters and words. The research team then looked for statistical relationships between reading scores and the structural features of specific subregions in the auditory cortex and anterior temporal lobes.
The findings point to a dual-route system where genetics and experience play distinct roles. In the phonological route, the researchers found that a higher myelin proxy in the left medial belt of the auditory cortex was associated with lower reading scores.
While this physical brain trait was predominantly shaped by environmental factors rather than being highly heritable, its specific relationship with reading ability showed a stable genetic correlation. The medial belt processes basic sound rhythms and syllable boundaries, which is an early step in learning to decode words. In contrast, cortical thickness in the auditory core, the area responsible for processing fine-grained sound details like individual consonants and vowels, was positively associated with reading ability. This increased thickness did not show a genetic link, which suggests it builds up through the experience of reading.
A similar division appeared in the semantic route. A larger cortical surface area in two specific meaning-processing hubs, the left anterior middle temporal gyrus and the right dorsal temporal pole, was positively associated with better reading skills. Twin comparisons indicated that this expanded surface area was strongly heritable. Follow-up tests showed that these exact brain areas predicted how well participants performed on a vocabulary comprehension task, linking the heritable brain trait specifically to semantic processing.
“The genetic relationships between reading skill and regions in the anterior temporal lobes surprised me,” Roll noted. “These areas are involved in accessing word meaning and identifying faces and familiar visual forms. It is possible that partly inherited differences in these systems give some people an advantage when they begin learning to identify written words and connect them with meaning.”
The team also analyzed the brain’s white matter tracts in a subset of 1,036 participants. They found that the structural integrity of the inferior fronto-occipital fasciculus and the arcuate fasciculus predicted reading ability independently of genetic influences. This indicates that as people practice reading, the communication pathways that integrate sound and meaning become optimized through experience.
Ultimately, these physical and genetic variations translate into distinct learning styles. “Our different starting points and experiences shape the brain’s routes to reading, producing a unique reading experience for each of us,” Roll said. “Some people may rely more strongly on an inner voice, while others may connect written word forms more directly to meaning.”
The findings are in line with research covered by PsyPost in 2025, which observed that better reading ability across the general population was associated with a thicker left auditory cortex and a larger left anterior temporal lobe. The current study also aligns broadly with another study covered by PsyPost in 2025 that linked genetic factors to altered white matter and brain volume in language areas. That earlier study, however, specifically examined genetic risk scores for dyslexia rather than directly measuring heritability and continuous reading ability.
As with all research, there are a few things to keep in mind. The image ratio used to estimate myelin is an indirect measure. While it generally correlates with myelin content, it can also reflect other cellular variations like the density of brain cells or the orientation of nerve fibers.
“Some of the brain features associated with reading ability in this study have previously been linked to dyslexia,” Roll pointed out. “Importantly, I found continuous relationships with reading ability across the population in a group without known dyslexia. This does not diminish the difficulties experienced by people with dyslexia, but suggests that there may also be a broader gray zone of less striking reading difficulties that deserves attention.”
He also cautioned that the structural correlations, while systematic, are not massive. “The effects are modest, which is what we would expect for a complex ability like reading that depends on many biological and environmental factors,” Roll explained. “But they were detected in a large sample of more than a thousand people and reveal systematic differences across the population.”
It is also important to note that the study looked at a single snapshot in time using young adults. Because the researchers compared twins to estimate heritability, they can confidently say certain traits have a genetic basis. However, estimating how much a brain structure changes purely due to reading experience over a lifetime would require tracking the same individuals from childhood through adulthood.
Future studies might look at how these specific structural differences respond to reading interventions in children. Because the study provides evidence that reading relies on both sound-based and meaning-based brain hubs, educators might find that mixing phonological training with vocabulary building helps support the diverse natural brain profiles found in any classroom. “One practical message is that we should recognize that children come to reading with different starting points and may need different kinds of support,” Roll added.
“I would like to extend this approach beyond reading and map more specific language abilities onto genetic and fine-grained measures of brain structure,” Roll said regarding his future research. “I am particularly interested in the structural basis of auditory abilities involved in analyzing speech sounds and speech melody. Ultimately, I would like to understand how inherited differences and experience interact to build the brain networks that support language.”
The study, “Heritable and experience-dependent cortical traits of reading ability,” was authored by Mikael Roll.
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