Genotype by Environment Interaction in Adolescents’ Cognitive Aptitude

Abstract

In a replication of Turkheimer, Haley, Waldron, D'Onofrio, Gottesman II (2003, Socioeconomic status modifies heritability of IQ in young children. Psychological Science, 14:623-628), we investigate genotype-environment (G × E) interaction in the cognitive aptitude of 839 twin pairs who completed the National Merit Scholastic Qualifying Test in 1962. Shared environmental influences were stronger for adolescents from poorer homes, while genetic influences were stronger for adolescents from more affluent homes. No significant differences were found between parental income and parental education interaction effects. Results suggest that environmental differences between middle-to upper-class families influence the expression of genetic potential for intelligence, as has previously been suggested by Bronfenbrenner and Ceci's (1994, Nature-nurture reconceptualized in developmental perspective: a bioecological model Psychological Review, 101:568-586) bioecological model. KeywordsGene-environment interaction; Intelligence; Socioeconomic status; Cognitive aptitude Turkheimer et al. (2003) published a report of genotype-environment (G × E) interaction in the intelligence of young children. In a sample of 7-year old children from the National Perinatal Collaborative Project, the genetic and shared environmental influences on IQ, as measured by the Weschler Intelligence Scale for Children-Revised (WISC-R), were modified by the socioeconomic status (SES) of the children. For disadvantaged children, shared environmental influences accounted for nearly 60% of the variance in IQ, while genetic factors accounted for negligible variance. In advantaged children, the pattern was nearly the reverse.Although the above results are congruent with some previous research (for reviews see or Turkheimer et al. 2003, researchers have not always found clear evidence for G × E interaction in cognitive ability (e.g., Scarr 1981, Van den Oord and Rowe 1997), leaving open the extent to which the results Turkheimer et al. present can be generalized beyond the NCPP sample. This paper presents results of a replication of Turkheimer et al.'s (2003) investigation; however, there are several key changes in the current study. First, the

Correlations between cannabis use and IQ change in the Dunedin cohort are consistent with confounding from socioeconomic status

“…As a consequence, the well-established increase in heritability of IQ with age (21,22) will be driven by an even stronger increase in heritability of IQ within low-SES groups. This result would be consistent with the heritability measures for high-SES individuals being high already in childhood and adolescence (19,23).…”

“…As a consequence, the well-established increase in heritability of IQ with age (21, 22) will be driven by an even stronger increase in heritability of IQ within low-SES groups. This result would be consistent with the heritability measures for high-SES individuals being high already in childhood and adolescence (19,23).It is worth noting that the relationship between SES and IQ change is supported empirically and has validity independently of the Flynn-Dickens theory that led us to it. Empirical research on how IQ trajectories differ with individual characteristics indicates that age-related cognitive decline is higher for some minorities, those with low education, and those in jail (24,25).…”

Differences in genetic and environmental influences on the human cerebral cortex associated with development during childhood and adolescence

“…It has been demonstrated that a large sample is necessary to detect C , and the present study may lack sufficient power. Studies of heritability of cognition have found that there is a gene 3 environment interaction such that shared environmental factors become more prominent relative to genetic factors as socioeconomic conditions worsen [Harden et al, 2007;Turkheimer et al, 2003]. The subjects in the current study came primarily from middle to high socioeconomic settings.…”

Environmental and genetic determinants of innovativeness in a natural population of birds

“…Many of these studies report differences between groups that vary in dominance, for example between the ages and sexes, but some studies have explicitly shown a negative correlation between innovativeness and competitive ability over and above these dominance groups [39]. Although these effects tend to be interpreted as environmentally mediated, a gene  environment interaction cannot be easily ruled out since additive genetic differences may only be apparent at a specific age or in a specific environment [64,65]. Clearly, in addition to the possibility that innovativeness has a heritable component of variation, a range of environmental factors are also likely to explain the tendency to innovate but the importance of these in natural populations has not been tested.…”