Socioeconomic context influences the heritability of child cortical structure

Children differ in brain cortical morphometry and microstructure, which together form the structural foundation for cognition. Cortical structure is highly heritable, but whether heritability varies across socioeconomic status (SES) is unknown. In this preregistered study, we estimated single-nucleotide polymorphism (SNP)-based heritability of cortical thickness, surface area, sulcal depth, and grey-/white-matter contrast (GWC) among 9,080 US 10-year-olds. We then tested whether genetic and environmental influences were moderated by parental SES, defined as a composite of income, education, and neighbourhood deprivation. Cortical thickness and surface area showed high heritability, while sulcal depth and GWC exhibited moderate heritability. However, among children from lower-SES backgrounds, cortical differences were less genetically influenced and more influenced by unique environmental factors, at times exceeding genetic contributions. These findings suggest that in contexts of socioeconomic disadvantage, children’s brain structure reflect lived experience more strongly than previously recognized.