Gene-Environment Interactions in Mathematical Learning: Examining Heritability, Classroom Environment, and Achievement in Nigerian Twin Pairs

This study examines gene-environment interactions in mathematical learning by investigating heritability estimates, classroom environment moderators, and their joint effects on mathematical achievement in Nigerian twin pairs, representing the first quantitative genetic educational psychology study conducted in a Nigerian school population. Behaviour genetics approaches have generated substantial evidence on the heritability of mathematical ability in Western twin studies, but their application to African populations, where genetic diversity, nutritional environments, and educational conditions differ fundamentally, has been wholly absent from the literature. The study recruits 280 twin pairs aged 8 to 12, comprising monozygotic and dizygotic twins, from primary and junior secondary schools across Lagos, Abuja, Enugu, and Kano States. Mathematical achievement was assessed using the Nigerian Primary Mathematics Achievement Battery, classroom environment quality was evaluated through the Classroom Assessment Scoring System, and genetic zygosity was confirmed using buccal swab DNA analysis. Classical twin model analyses decomposing variance into additive genetic, shared environmental, and non-shared environmental components, and gene-environment interaction models testing whether heritability estimates vary as a function of classroom quality, constitute the primary analyses. Results indicate substantial heritability of mathematical achievement, with classroom environment functioning as a significant moderator: heritability estimates are amplified in high-quality classrooms and suppressed in low-quality environments, suggesting that improving classroom quality in Nigeria may paradoxically both raise average achievement and increase individual differences. This study makes an original methodological and substantive contribution to educational psychology and behaviour genetics in Africa. Keywords: gene-environment interaction, mathematical learning, twin study, heritability, Nigerian schools.