Although much genetic research has addressed normal variation in intelligence, little is known about the etiology of high cognitive abilities. Using data from 11,000 twin pairs (age range = 6-71 years) from the genetics of high cognitive abilities consortium, we investigated the genetic and environmental etiologies of high general cognitive ability (g). Age-appropriate psychometric cognitive tests were administered to the twins and used to create g scores standardized within each study. Liability-threshold model fitting was used to estimate genetic and environmental parameters for the top 15% of the distribution of g. Genetic influence for high g was substantial (0.50, with a 95% confidence interval of 0.41-0.60). Shared environmental influences were moderate (0.28, 0.19-0.37). We conclude that genetic variation contributes substantially to high g in Australia, the Netherlands, the United Kingdom and the United States.
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Acknowledgments The GHCA consortium is supported by a grant from the John Templeton Foundation (#13575). The opinions expressed in this report are those of the authors and do not necessarily reflect the views of the John Templeton Foundation. We thank Andrew McMillan for his support with the data management. Support for the GHCA consortium members’ twin studies include: Western Reserve Reading Project (Ohio): US National Institute of Child health and Human Development (HD038075 and HD046167). The Twins Early Development Study (United Kingdom): UK Medical Research Council (G0500079) and the US National Institute of Child Health and Human Development (HD44454 and HD46167). Minnesota Twin Family Study (USA): USPHS grants AA009367, R01 DA005147 & R01 DA013240. Colorado Twin Studies (USA): LTS: HD19802, HD010333, HD18426, MH043899, and the MacArthur Foundation; CTS: VA1296.07.1629B and DA011015; CLDRC: HD11681, HD027802. Twin Cognition Study (Australia): the Australian Research Council (A7960034, A79906588, A79801419, DP0212016, DP0343921) and The Human Frontier Science Program (RG0154.1998-B). The Netherlands Twin Register: Dutch Organization for Scientific Research (NWO 051.02.060; NWO 480-04-004; NWO 575-25-012; NWO/SPI 56-464-14192) and Human Frontiers of Science Program (RG0154/1998-B). D Posthuma is supported by NWO/MaGW VIDI-016-065-318.
- High cognitive ability