2013/09/03 by Timothy C. Bates, Gary J. Lewis, Alexander Weiß · 4 citations
Psychology · Biochemistry, Genetics and Molecular Biology · Medicine · #Cognitive Abilities and Testing #Genetic Associations and Epidemiology #Birth, Development, and Health
paper · doi:10.1177/0956797613488394
openalex publication_date 2013/09/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Studies of intelligence in children reveal significantly higher heritability among groups with high socioeconomic status (SES) than among groups with low SES. These interaction effects, however, have not been examined in adults, when between-families environmental effects are reduced. Using 1,702 adult twins (aged 24-84) for whom intelligence assessment data were available, we tested for interactions between childhood SES and genetic effects, between-families environmental effects, and unique environmental effects. Higher SES was associated with higher mean intelligence scores. Moreover, the magnitude of genetic influences on intelligence was proportional to SES. By contrast, environmental influences were constant. These results suggest that rather than setting lower and upper bounds on intelligence, genes multiply environmental inputs that support intellectual growth. This mechanism implies that increasing SES may raise average intelligence but also magnifies individual differences in intelligence.