Abstract
Abstract. An association between intelligence at age 7 and a set of five single-nucleotide polymorphisms (SNPs) has been identified and replicated. We used this composite SNP set to investigate whether the associations differ between boys and girls for general cognitive ability at ages 2, 3, 4, 7, 9, and 10 years. In a longitudinal community sample of British twins aged 2-10 (n > 4,000 individuals), we found that the SNP set is more strongly associated with intelligence in males than in females at ages 7, 9, and 10 and the difference is significant at 10. If this finding replicates in other studies, these results will constitute the first evidence of the same autosomal genes acting differently on intelligence in the two sexes.
References
(2005). Association analysis of mild mental impairment using DNA pooling to screen 432 brain-expressed single-nucleotide polymorphisms. Molecular Psychiatry, 10, 384–392
(2005). SNPs, microarrays and pooled DNA: Identification of four loci associated with mild mental impairment in a sample of 6,000 children. Human Molecular Genetics, 14, 1315–1325
(2005). X-inactivation profile reveals extensive variability in X-linked gene expression in females. Nature, 434, 400–404
(1992). Sex-differences in variability in intellectual abilities - a new look at an old controversy. Review of Educational Research, 62, 61–84
(1994). Gender differences in variability in intellectual abilities: A cross-cultural perspective. Sex Roles, 30, 81–92
(1996). Sexual selection and sex differences in mathematical abilities. Behavioral and Brain Sciences, 19, 229–284
(2005). The neuroanatomy of general intelligence: Sex matters. Neuroimage, 25, 320–327
(1995). Sex-differences in mental test-scores, variability, and numbers of high-scoring individuals. Science, 269, 41–45
(2005). The gender similarities hypothesis. American Psychologist, 60, 581–592
(2006). Males have greater g: Sex differences in general mental ability from 100,000 17- to 18-year-olds on the scholastic assessment test. Intelligence, 34, 479–486
(2005). Sex differences in n-acetylaspartate correlates of general intelligence: An H-1-MRS study of normal human brain. Neuroimage, 26, 965–972
(2002). Sex differences in genetic and environmental risk factors for irrational fears and phobias. Psychological Medicine, 32, 209–217
(1994). Adaptive sequential testing for educational-evaluation. Electronics and Communications in Japan Part III - Fundamental Electronic Science, 77, 1–12
(1974). The psychology of sex differences. Stanford, CA: Stanford University Press
(2004). The hidden genetic program of complex organisms. Scientific American, 291(4), 60–67
(2007). Twins' Early Development Study (TEDS). A multivariate, longitudinal genetic investigation of language, cognition, and behavior problems from childhood through adolescence. Twin Research and Human Genetics, 10, 96–105
g in middle childhood: Moderate genetic and shared environmental influence using diverse measures of general cognitive ability at 7, 9, and 10 years in a large population sample of twins. Intelligence,
in press(2002). Testing cognitive abilities by telephone in a sample of 6- to 8-year-olds. Intelligence, 30, 353–360
(2003). Sex differences in heritability of BMI: A comparative study of results from twin studies in eight countries. Twin Research, 6, 409–421
(2002). DNA pooling: A tool for large-scale association studies. Nature Review Genetics, 3, 862–871
(2005). Sex differences in intrinsic aptitude for mathematics and science? A critical review. American Psychologist, 60, 950–958
(2003). Phenotypic “g” early in life: On the etiology of general cognitive ability in a large population sample of twin children aged 2 to 4 years. Intelligence, 31, 195–210
(2003). Sex differences in genetic and environmental effects on aggression. Aggressive Behavior, 29, 55–68