Genetic and Environmental Contributions to General Cognitive Ability Through the First 16 Years of Life.

Abstract

The genetic and environmental contributions to the development of general cognitive ability throughout the first 16 years of life were examined using sibling data from the Colorado Adoption Project. Correlations were analyzed along with structural equation models to characterize the genetic and environmental influences on longitudinal stability and instability. Intraclass correlations reflected both considerable genetic influence at each age and modest shared environmental influence within and across ages. Modeling results suggested that genetic factors mediated phenotypic stability throughout this entire period, whereas most age-to-age instability appeared to be due to nonshared environmental influences.

Individual differences in executive functions are almost entirely genetic in origin.

“…Previous research on the developmental stability and change of cognitive abilities in this age range suggest that genetic effects contribute to stability of scores, while instability is due primarily to nonshared environment. For example, Petrill et al (2004) found that the genetic correlation between IQ scores at year 12 and year 16 was 1.0, strongly suggesting that there are no new sources of genetic variation in this age range (which is quite a bit larger than the range of 16 to 17 in the current study). Hence, we think it unlikely that the one-year gap between the two sessions substantially lowered the genetic correlations between the executive functions at age 17 and the other cognitive abilities at age 16.…”

Genetic and Environmental Stability of Intelligence in Childhood and Adolescence

“…The environment shared by family members appeared to contribute to stability to a moderate degree, while environmental factors unique to family members contributed mainly to innovation (i.e., to temporal instability). Similarly, the observed stability in the g factor was driven primarily by genetic factors: the additive genetic g factor displayed near complete stability, the common environmental g factor was generally stable but explained less of the phenotypic variance than the A g factor, while the unique environmental g factor was modestly stable but explained only a minor fraction of the phenotypic variance in g. An age-related increase in heritability accompanied by a relative decline in common environmental variance, expected based on the literature (e.g., Bartels et al, 2002;Bishop et al, 2003;Boomsma & van Baal, 1998;Deary et al, 2006;Haworth et al, 2009;Hoekstra et al, 2007;McGue et al, 1993;Petrill et al, 2004;Plomin, 1986;Polderman et al, 2006), was observed. In addition, the cross-subscale stability was consistently low, indicating a small to non-existent contribution of one domain of intelligence to another over time.…”

“…The findings emerging from twin and family studies have univocally indicated: (1) a role of genetic factors in the etiology of intelligence (e.g., Bouchard & McGue, 1981;Deary et al, 2006;Plomin & Spinath, 2004;Plomin et al, 2008), and (2) an age-dependent pattern of heritability, with individual differences in late adolescence and adulthood being more strongly influenced by genetic factors than those in childhood (the heritability estimates typically ranging from ß20% in infancy to ß40-50% in middle childhood and ß60-80% in adulthood; e.g., Bartels et al, 2002;Bishop et al, 2003;Boomsma & van Baal, 1998;Deary et al, 2006;Haworth et al, 2009;Hoekstra et al, 2007;McGue et al, 1993;Petrill et al, 2004;Plomin, 1986;Polderman et al, 2006). Environmental factors that contribute to similarity between family members (e.g., shared family environment) typically decline in etiological relevance throughout childhood and adolescence, while environmental factors that Sanja Franić, Conor V. Dolan, Catherina E.M. van Beijsterveldt, Hilleke E. Hulshoff Pol, Meike Bartels & Dorret I. Boomsma facilitate differentiation between family members appear to play a persistently modest to moderate role (e.g., Bartels et al, 2002;Boomsma & van Baal, 1998;Haworth et al, 2009).…”

Infant temperament and eating style predict change in standardized weight status and obesity risk at 6 years of age

“…Data were also collected on nonadoptive families that were matched with respect to infant sex, number of siblings, and paternal age, occupational status and education. 30,31 The year 1 assessment of infant temperament and eating style measures was conducted either with the biological parents (that is, in the case of children from nonadoptive families, N ¼ 245) or with adoptive parents (that is, in the case of children from adoptive families, N ¼ 242). Biological parents were recruited through two Denver adoption agencies, which placed infants in temporary foster homes until being placed with their permanent adoptive families.…”