Explaining the Increasing Heritability of Cognitive Ability Across Development: A Meta-Analysis of Longitudinal Twin and Adoption Studies

“This is advantageous because it allows the results of the model to generalize beyond the studies that were included in the analysis to a theoretical population of heterogeneous studies (Hedges & Vevea, 1998).”

“Scarr and McCartney (1983) suggested that one’s genotype drives development, because “it is the discriminator of what environments are actually experienced” (p. 425).”

“This analysis hinges on whether more genetically similar siblings are also more similar in their level of cognitive ability (Neale & Cardon, 1992).”

“First, we sought to replicate the trend of increasing heritability using only longitudinal data, which avoids validity threats associated with cross-sectional approaches (e.g., cohort effects; Baltes, 1968; Flynn, 1987).”

“One might expect this rationale to apply particularly well to a highly complex psychological outcome, such as cognition, which is thought to develop as a result of experience-dependent neural connections (Garlick, 2002) and is known to depend on environmental quality and educational experience (Ceci, 1991; Nelson et a…”

“One might expect this rationale to apply particularly well to a highly complex psychological outcome, such as cognition, which is thought to develop as a result of experience-dependent neural connections (Garlick, 2002) and is known to depend on environmental quality and educational experience (Ceci, 1991; Nelson et a…”

“…for increasingly less variation in psychological outcomes as children develop, and variation in environmental experiences will account for increasingly more of the variation in psychological outcomes (e.g., see Fryer & Levitt, 2006; Spelke, 2005; cf. McGue, Bouchard, Iacono, & Lykken, 1993).”

“Somewhat counterintuitively, a number of studies have indicated precisely the opposite developmental pattern with respect to the genetic and environmental influences on cognition.”

“Additional supporting information may be found at http://pss .sagepub.com/content/by/supplemental-data”

“…longitudinal behavioral genetic models to meta-analytic data on twins and siblings, we sought to identify the mechanisms underlying the well-established finding that genetic influences on cognitive abilities increase over the course of development (Bergen et al., 2007; Haworth et al., 2010).”

“First, we sought to replicate the trend of increasing heritability using only longitudinal data, which avoids validity threats associated with cross-sectional approaches (e.g., cohort effects; Baltes, 1968; Flynn, 1987).”

“…longitudinal behavioral genetic models to meta-analytic data on twins and siblings, we sought to identify the mechanisms underlying the well-established finding that genetic influences on cognitive abilities increase over the course of development (Bergen et al., 2007; Haworth et al., 2010).”

“…forces result in decreased genetic influences on cognition with age, or that genetic influences are immutable and entirely apparent at birth, the field of developmental behavior genetics has uncovered evidence that the genetic influences on intelligence increase with age (Plomin & Spinath, 2004).”

“McCartney, Harris, and Bernieri (1990) provided some of the earliest, persuasive evidence of this trend.”

“…to apply particularly well to a highly complex psychological outcome, such as cognition, which is thought to develop as a result of experience-dependent neural connections (Garlick, 2002) and is known to depend on environmental quality and educational experience (Ceci, 1991; Nelson et al., 2007).”

“For example, small genetically influenced differences in cognitive ability can lead to differences in aspects of the environment provided by parents, teachers, and peers that in turn influence subsequent cognitive development (Tucker-Drob & Harden, 2012a, 2012b).”

“This may be due to the unique modeling approach taken by the original authors or to potential differences in developmental processes across populations (e.g., Hanscombe et al., 2012).”

“…for increasingly less variation in psychological outcomes as children develop, and variation in environmental experiences will account for increasingly more of the variation in psychological outcomes (e.g., see Fryer & Levitt, 2006; Spelke, 2005; cf. McGue, Bouchard, Iacono, & Lykken, 1993).”

“Rather than evaluating a model that included multiple indicators of cognition at a given time point, Davis et al. (2009) constructed a model that included cognition at multiple time points to form each latent variable.”

“However, as all children ultimately enter the educational system, standardized educational practices can serve to equalize differences between families (Downey, von Hippel, & Broh, 2004; Tucker-Drob, 2012).”

“Two possibilities are what can be termed innovation and amplification (Plomin, 1986; Plomin & DeFries, 1985).”

“Indeed, there is consistent evidence of increasing heritability of cognitive abilities during development, with meta-analyses indicating increases from approximately 10% in infancy to approximately 70% by late adolescence (Briley & Tucker-Drob, 2013; Haworth et al., 2010).”

“A meta-analysis of results from longitudinal twin and adoption studies also found increases in heritability from infancy through adolescence (Briley & Tucker-Drob, 2013).”