The Wilson Effect: The Increase in Heritability of IQ With Age

  title={The Wilson Effect: The Increase in Heritability of IQ With Age},
  author={Thomas J. Jr. Bouchard},
  journal={Twin Research and Human Genetics},
  pages={923 - 930}
  • T. Bouchard
  • Published 7 August 2013
  • Psychology
  • Twin Research and Human Genetics
Ronald Wilson presented the first clear and compelling evidence that the heritability of IQ increases with age. We propose to call the phenomenon ‘The Wilson Effect’ and we document the effect diagrammatically with key twin and adoption studies, including twins reared apart, that have been carried out at various ages and in a large number of different settings. The results show that the heritability of IQ reaches an asymptote at about 0.80 at 18–20 years of age and continuing at that level well… 
A Meta-analysis of Heritability of Cognitive Aging: Minding the “Missing Heritability” Gap
Meta-analyses of age trends in heritability of specific cognitive abilities and considers the profile of genetic and environmental factors contributing to cognitive aging to address the ‘missing heritability’ issue indicate that verbal ability demonstrated declining heritability, after about age 60, as did spatial ability and perceptual speed more modestly.
Polygenic and socioeconomic risk for high body mass index: 69 years of follow-up across life
A birth cohort study is used to investigate differences in association and explained variance in the polygenic prediction of BMI from infancy to old age in a single sample and finds the likely independent influences of polygenic and socioeconomic factors on BMI across life.
A genome-wide association study for extremely high intelligence
This study shows the utility of extreme trait selection for genetic study of intelligence and suggests that extremely high intelligence is continuous genetically with normal-range intelligence in the population.
Parental education accounts for variability in the IQs of probands with Down syndrome: A longitudinal study
Despite the expected IQ deficits observed in trisomy 21 probands, parental education may still contribute to the variability of probands' cognitive abilities, consistent with the literature noting increasing heritability of IQ with development.
Genetic and phenotypic associations between brain imaging, psychopathology and educational attainment in children aged 9-11
The results highlight the potential of multivariate models to better understand the transdiagnostic and distributed relationships between mental health and brain structure in late childhood.
Cultural Evolution of Genetic Heritability
This framework helps explain why it is easier to discover genes for deficiencies than genes for abilities, and predicts the ways in which heritability should differ between societies, between socioeconomic levels within some societies but not others, and over the life course.
Grandchild’s IQ is associated with grandparental environments prior to the birth of the parents
GDP at grandparents’ birth produced independent associations of reduced IQ with higher GDP; this was particularly true of paternal grandmothers, especially in grandsons.
Geographic Clustering of Polygenic Scores at Different Stages of the Life Course
The ecological clustering of polygenic scores may denote a new environmental factor in gene-environment research and the possible mechanisms that underlie this association are discussed.


The heritability of general cognitive ability increases linearly from childhood to young adulthood
It is shown for general cognitive ability that, to the contrary, genetic influence increases with age, and this finding suggests new ways of thinking about the interface between nature and nurture during the school years.
Differences in genetic and environmental influences on the human cerebral cortex associated with development during childhood and adolescence
The observation that regions associated with complex cognitive processes such as language, tool use, and executive function are more heritable in adolescents than children is consistent with previous studies showing that IQ becomes increasingly heritable with maturity.
Genetic influences on cognitive functions in the elderly: A selective review of twin studies
Dramatic Increase in Heritability of Cognitive Development from Early to Middle Childhood
Despite increasing importance of genetic influences and declining influence of shared environment, similar genetic and shared environmental factors affect g from early to middle childhood, as indicated by a cross-age genetic correlation of .57 and a shared environmental correlation of%.
Heritability of cognitive abilities in adult twins: Comparison of Minnesota and Swedish data
Heritability estimates and the factor structure of cognitive abilities could be equated across younger twins and middle-aged twins from both studies, suggesting stability of heritability during adulthood.
The Louisville Twin Study: developmental synchronies in behavior.
The overall results pointed to a strong developmental thrust in the growth of intelligence, which was principally guided by an intrinsic genetic ground plan, and Qualitative features of home and family did not add significantly to prediction of offspring IQ.
Intelligence: new findings and theoretical developments.
The relationship between working memory and intelligence, the apparent contradiction between strong heritability effects on IQ, whether a general intelligence factor could arise from initially largely independent cognitive skills, the relation between self-regulation and Cognitive skills, and the effects of stress on intelligence are reported.
Genetic influence on human intelligence (Spearman's g): How much?
The application of ‘strong inference’, via the use of structural equation models in the domain of human intelligence, is described, and its utility is demonstrated as a means of refuting well formulated scientific hypotheses.