Genetic and environmental influences on the Verbal-Perceptual-Image Rotation (VPR) model of the structure of mental abilities in the Minnesota study of twins reared apart

Why are cognitive abilities of children so different across countries? The link between major socioeconomic factors and PISA test scores

“…In the short term, children's schooling has a modest direct impact (β=.27) on their cognitive ability, but in the long-term, when the children become parents, their educational background will result in a large total effect (β=.55) on the ability of the next generation, indirectly through the effects of fertility, household income, and children's schooling, as we have found in this study. Our study corroborates evidence that intergenerational transmission of human capital is more likely to occur through a stimulating environment provided by well-educated parents (Björklund, Lindahl, & Plug, 2006;Johnson et al, 2007;Sacerdote, 2002;Umek, Podlesek, & Fekonja, 2005). Therefore, as the basis of societal progress across generations, we suggest that formal education should not merely focus on attracting children to stay longer in school through an old-fashioned examination-oriented education system.…”

“…On the other hand, some studies argue that parents' income and educational levels are antecedent factors that influence variation in IQ-associated socioeconomic factors (e.g., Bacharach & Baumeister, 1998;Johnson et al, 2007). From this it can be understood that, in the long term, these socioeconomic factors are linked in a way through which a variable can indirectly determine children's IQ through the effects of other variables.…”

Genetic and environmental contributions to cognitive structure in Australian twins: A reappraisal

“…The best-fitting model had a zero contribution from the environment shared by the twins, a substantial contribution at the general factor level from additive genes (averaging 31% of the variance across the subtests), a modest additive genetic contribution from four intermediate-level factors (mean of 12%) and a roughly equivalent amount of subtest-specific genetic variance (mean of 14%). In a third study, Johnson and her colleagues fitted a hierarchical model to data from 42 cognitive tests administered to 126 twin pairs (mean age 42.7, SD 13.6. range 18 to 79) from the Minnesota Study of Twins Reared Apart (Johnson et al, 2007). They concluded: "Our results demonstrated high consistency between the environmental and phenotypic structure of mental ability as well as between the genetic and phenotypic structure" (p. 559).…”

Genetic foundations of human intelligence

“…None of the classic papers we cite here is recent, but this is precisely the point: more recent studies have done nothing to change the conclusion that there are substantial genetic influences on human intelligence, ranging from 30 to 80% of its total variance including the error with which it is measured. By way of comparison, genetic influences on broad domains of cognitive ability are generally similar Posthuma et al 2001Posthuma et al , 2003Rijsdijk et al 2002), with the exception of memory, which tends to show smaller genetic influence (Finkel et al 1995;Johnson et al 2007;Pedersen et al 1992). Consistent with the presence therein of tests' error variances, genetic influences on abilities unique to specific tests are generally substantially lower.…”

“…The heritability of g increases with age (McCartney et al 1990;McGue et al 1993;Plomin 1986;Wilson 1978). Again we cite older studies because it is well established that heritability increases from about 30% in very young childhood (Spinath et al 2003) to as much as 80% in adulthood (Edmonds et al 2008;Jacobs et al 2007;Johnson et al 2007). More recent studies have tended to focus on measuring the extent to which genetic influences contribute to stability and change in g. For example, using Dutch twin pairs assessed at ages 5, 7, 10, 12, and 18 years, Hoekstra et al (2007) found that the heritability of verbal ability increased from 48% at age 5 to 84% at age 18, while the heritability of nonverbal ability increased from 64% at age 5 to 74% at age 18.…”