2003/11/01 by Eric Turkheimer, Andreana P. Haley, Mary Waldron +2 · 26 citations
Psychology · Social Sciences · #Child and Adolescent Psychosocial and Emotional Development #Cognitive Abilities and Testing #Early Childhood Education and Development
paper · doi:10.1046/j.0956-7976.2003.psci_1475.x
openalex publication_date 2003/11/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
Scores on the Wechsler Intelligence Scale for Children were analyzed in a sample of 7-year-old twins from the National Collaborative Perinatal Project. A substantial proportion of the twins were raised in families living near or below the poverty level. Biometric analyses were conducted using models allowing for components attributable to the additive effects of genotype, shared environment, and nonshared environment to interact with socioeconomic status (SES) measured as a continuous variable. Results demonstrate that the proportions of IQ variance attributable to genes and environment vary nonlinearly with SES. The models suggest that in impoverished families, 60% of the variance in IQ is accounted for by the shared environment, and the contribution of genes is close to zero; in affluent families, the result is almost exactly the reverse.