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1 ROBERT PLOMIN on Behavioral Genetics Genetic Links Common Genetic links • Background – Why has educational psychology ben so slow ROBERT PLOMIN to accept genetics? on Behavioral Genetics • Beyond nature vs. nurture – 3 findings from genetic research with far- reaching implications for education: October, 2004 The nature of nurture The abnormal is normal Generalist genes • Molecular Genetics Quantitative genetics: twin and adoption studies Common medical disorders Identical twins Fraternal twins (monozygotic, MZ) (dizygotic, DZ) 1 Twin concordances in TEDS at 7 years Twins Early Development Study (TEDS) for low reading and maths Perceptions of nature/nurture: % parents (N=1340) and teachers Beyond nature vs. nurture: (N=667) indicating that genes are at least as important as environment (Walker & Plomin, Ed. Psych., in press) The nature of nurture • Genetic influence on experience • Genotype-environment correlation – Children’s genetic propensities are correlated with their experiences passive evocative active 2 Beyond nature vs. nurture: Genotype-environment correlation The nature of nurture • Passive • Genotype-environment correlation – e.g., family background (SES) and school – Children’s genetic propensities are correlated with achievement their experiences passive • Evocative evocative – Children evoke experiences for genetic reasons Active • Active • Molecular genetics – Children actively create environments that foster – Find genes associated with learning experiences their genetic propensities Beyond nature vs. nurture: The one-gene one-disability (OGOD) model The abnormal is normal • Common learning disabilities are the quantitative extreme of the same genetic and environmental factors responsible for normal variation in learning abilities. • There are no common learning disabilities, just the extremes of normal variation. 3 OGOD (rare) and QTL (common) disorders The quantitative trait locus (QTL) model Beyond nature vs. nurture: OGOD (rare) and QTL (common) disorders The abnormal is normal • Common learning disabilities are the quantitative extreme of the same genetic and environmental factors responsible for normal variation in learning abilities. – There are no common learning disabilities, just the extremes of normal variation. • Molecular genetics – Genes associated with reading disability will also be associated with reading ability throughout the normal range. 4 Beyond nature vs. nurture: Phenotypic overlap between ‘Generalist genes’ learning disabilities • The same set of genes affects diverse learning abilities and disabilities Reading Mathematics Disability Disability – Genetic homogeneity rather than heterogeneity Comorbidity Genetic overlap between Beyond nature vs. nurture: learning disabilities ‘Generalist genes’ Reading Mathematics • The same set of genes affects diverse Disability Disability learning abilities and disabilities • Molecular genetics – Look for generalist genes, not just specialist genes Genetic Comorbidity 5 Genetic links • Background – Why has educational psychology been so slow to accept genetics? • Beyond nature vs. nurture – 3 findings from genetic research with far-reaching implications for education: The nature of nurture The abnormal is normal Generalist genes • Molecular Genetics Need to break the 1% QTL barrier Breaking the 1% QTL barrier • Large samples – e.g., 500 cases, 500 controls • Systematic search – At least 100,000 DNA markers (SNPs) Environmental Genetic Variance Variance • Cost – 1000 subjects, 100,000 SNPs ~ $20 million 6 Microarrays: 1000 subjects, 100,000 SNPs ~ $1 million DNA pooling 500 cases, 500 controls Æ 2 DNA pools 500 cases in one DNA pool Breaking the 1% QTL barrier: TEDS: molecular genetic studies of Pooled DNA on microarrays learning disabilities in 7-year-old children DNA pooling + Microarrays = $2000 • Mild mental impairment • Reading disability • Mathematics disability 7 Educational implications Research implications • Diagnosis – DNA-based diagnoses From finding genes to using genes – DNA routinely collected • Functional genomics • Treatment • DNA-tailored treatments • Behavioral genomics • Prevention – DNA as early-warning system Behavioral genetics in the postgenomic era = behavioral genomics 8 Video Chapter Complete • You have completed this video chapter • Use the bookmarks to review any portion of the chapter • Click on the download link to download a handout of the slides 9.
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