title: Literacy and numeracy are more heritable than intelligence in primary school.
abstract: Because literacy and numeracy are the focus of teaching in schools, whereas general cognitive ability (g, intelligence) is not, it would be reasonable to expect that literacy and numeracy are less heritable than g. Here, we directly compare heritabilities of multiple measures of literacy, numeracy, and g in a United Kingdom sample of 7,500 pairs of twins assessed longitudinally at ages 7, 9, and 12. We show that differences between children are significantly and substantially more heritable for literacy and numeracy than for g at ages 7 and 9, but not 12. We suggest that the reason for this counterintuitive result is that universal education in the early school years reduces environmental disparities so that individual differences that remain are to a greater extent due to genetic differences. In contrast, the heritability of g increases during development as individuals select and create their own environments correlated with their genetic propensities.
authors.affiliation: 1Laboratory for Cognitive Investigations and Behavioural Genetics, Department of Psychology, Tomsk State University.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Kovas
authors.forename: Ivan
authors.initials: I
authors.lastname: Voronin
authors.forename: Andrey
authors.initials: A
authors.lastname: Kaydalov
authors.forename: Sergey B
authors.initials: SB
authors.lastname: Malykh
authors.forename: Philip S
authors.initials: PS
authors.lastname: Dale
authors.forename: Robert
authors.initials: R
authors.lastname: Plomin
mesh_terms: D000124:Achievement; D000367:Age Factors; D001076:Aptitude; D002648:Child; D004777:Environment; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D007360:Intelligence / Q000235:genetics*; D008137:Longitudinal Studies; D008297:Male; D008433:Mathematics; D011932:Reading; D014429:Twins, Dizygotic / Q000235:genetics* / Q000523:psychology; D014430:Twins, Monozygotic / Q000235:genetics* / Q000523:psychology; D006113:United Kingdom
keywords: academic achievement; environmental effects; genetics; mathematical ability; reading