A Korean research team has confirmed that a child's brain does not simply grow larger as it matures, but is completed as the environment in which the child grows is added on top of an inborn genetic blueprint.
A joint team led by Ju Yoon-jeong of Sungkyunkwan University Samsung Advanced Institute for Health Sciences and Technology (SAIHST) and Cha Ji-uk of the Seoul National University Department of Psychology said on the 4th that it analyzed deoxyribonucleic acid (DNA) genomes, brain imaging, and behavioral data together for 8,620 children to determine how heredity affects brain structure and function and behavior. The findings were published in September in the international journal Nature Communications.
The team compared brain structure and activity data obtained through magnetic resonance imaging (MRI) with genetic information and psychological and behavioral indicators. As a result, children who had more genetic combinations related to cognitive ability had larger gray matter volume and higher cortical activity. By contrast, children with stronger genetic factors related to mental health issues such as depression, anxiety, and ADHD showed lower activity in specific brain regions. The researchers said the results are "evidence that heredity partly designs the direction and speed of brain growth in childhood."
They also found that some aspects of children's brain structure are influenced by genetics by around 20%, and that genetic factors act more strongly on gray matter development than on white matter. Gray matter is the region responsible for thinking and cognitive function, which means a child's development of thinking ability may be more strongly shaped by genetic factors.
However, while structural features such as the brain's shape and size are strongly influenced by genes, functional activity and the way it is consolidation are more affected by the environment. In other words, a child's brain is built on a genetic blueprint, but its function is tuned by external factors such as parents' mental health and the socioeconomic environment.
This study is the first in the world to use large-scale multimodal data to identify how genetic influences act across brain structure and function and behavior during neurodevelopment in childhood.
Ju Yoon-jeong said, "This shows that the brain in childhood is not simply a scaled-down version of an adult's, but a developmental stage where genes and environment interact in distinctive ways," adding, "If we track how the gene–brain–behavior consolidation changes after puberty, it will lead to precision medicine strategies to understand the mechanisms of mental illness onset and to screen high-risk groups early."
References
Nature Communications (2025), DOI: https://doi.org/10.1038/s41467-025-63312-6