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Cited by 139Cognitive Abilities and TestingIntergenerational and Educational Inequality StudiesGenetic Associations and Epidemiology

The Wilson Effect: The increase in heritability of IQ with age

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Bouchard, Thomas J.·2013·Twin Research and Human Genetics
DOI 10.1017/thg.2013.54
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Abstract

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 into adulthood. In the aggregate, the studies also confirm that shared environmental influence decreases across age, approximating about 0.10 at 18–20 years of age and continuing at that level into adulthood. These conclusions apply to the Westernized industrial democracies in which most of the studies have been carried out.

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  • The heritability of intelligence tends to increase with age, known as the Wilson effect.

    “The issue of age at assessment can be severe, as one of the most well-replicated findings about the behavior genetics of intelligence is that heritability tends to increase with age (this has been dubbed the Wilson effect; [29]).”

    From Global Ancestry and Cognitive Ability (2019) · cites this paper as [29]

  • The heritability of cognitive ability tends to increase from childhood into early adulthood (the Wilson Effect).

    “Although the heritability of cognitive ability tends to increase from childhood into early adulthood (this being the Wilson Effect; Bouchard, 2013)”

    From A Meta-Analysis of Spearman’s Hypothesis in the United States (2026) · cites this paper as Bouchard, 2013

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Research works printed but not linked: 25

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Authors
Bouchard, T. J.
Affiliations
University of Minnesota (US)
Corresponding author
Bouchard, Thomas J.
ORCID
Bouchard, Thomas J.
Venue
Twin Research and Human Genetics
Publisher
Cambridge University Press (CUP)
Published
2013-08-07
Volume
16
Issue
5
Pages
923-930
ISSN
  • 1832-4274 (ISSN-L)
  • 1839-2628
DOI
10.1017/thg.2013.54
OpenAlex
W2084122339
Cited by
139
References
5
Citations by year
2026: 14 · 2025: 13 · 2024: 13 · 2023: 16 · 2022: 13 · 2021: 9 · 2020: 10 · 2019: 11 · 2018: 12 · 2017: 9 · 2016: 7 · 2015: 8 · 2014: 4
FWCI
8.56
Type
journal article
Language
en
Open access
Licence
www.cambridge.org/core/terms (unspecified)
Locations
  • Twin Research and Human Genetics (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Social Sciences › Psychology › Experimental and Cognitive Psychology › Cognitive Abilities and Testing
  • Social Sciences › Sociology and Political Science › Intergenerational and Educational Inequality Studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Genetic Associations and Epidemiology
Keywords
Wilson effect, shared environment, twin studies, adoption studies, twins reared apart, intelligence
MeSH terms
Environment, Humans, Intelligence, Social Environment, Twins, Twins, Monozygotic

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