Does the heritability of cognitive abilities vary as a function of parental education? Evidence from a German twin sample

Abstract

A well-known hypothesis in the behavioral genetic literature predicts that the heritability of cognitive abilities is higher in the presence of higher socioeconomic contexts. However, studies suggest that the effect of socioeconomic status (SES) on the heritability of cognitive ability may not be universal, as it has mostly been demonstrated in the United States, but not in other Western nations. In the present study we tested whether the importance of genetic and environmental effects on cognitive abilities varies as a function of parental education in a German twin sample. Cognitive ability scores (general, verbal, and nonverbal) were obtained on 531 German twin pairs (192 monozygotic, 339 dizygotic, ranging from 7 to 14 years of age; Mage = 10.25, SD = 1.83). Data on parental education were available from mothers and fathers. Results for general cognitive ability and nonverbal ability indicated no significant gene x parental education interaction effect. For verbal ability, a significant nonshared environment (E) x parental education interaction was found in the direction of greater nonshared environmental influences on verbal abilities among children raised by more educated parents.

Socioeconomic status amplifies genetic effects in middle childhood in a large German twin sample

“…We found a main effect of SES on cognitive ability scores in the two younger cohorts, accompanied by a decrease of total phenotypic variance, as is typical in European samples (e.g., Bartels et al, 2009; Hanscombe et al, 2012; Spengler et al, 2018). However, in contrast to other European samples spanning middle childhood (Bartels et al, 2009; Hanscombe et al, 2012), our results in the youngest cohort support the Scarr-Rowe hypothesis.…”

“…Further, our results are limited to fluid cognitive abilities. Although existing evidence is mixed, some studies show differing results for abilities that are presumably more closely related to family SES (Grant et al, 2010; Spengler et al, 2018). Our results may also be limited by the fact that the ‘TwinLife’ sample is somewhat underrepresented with regard to lower SES levels compared to the German population (see Lang & Kottwitz, 2017).…”

“…This study only revealed a significant nonshared environmental x parental education interaction for verbal abilities. However, parental education as a proxy of SES might not adequately reflect the socioeconomic conditions in Germany, as discussed by the authors (Spengler et al, 2018). Other than gene × SES interactions, some studies also report significant environmental interactions of SES with shared-environmental variance being lower at higher levels of SES especially in young samples (Tucker-Drob et al, 2011; Turkheimer et al, 2003).…”

“…However, without knowledge of zygosity, this latter study had to rely on matched birth and school records from twins and siblings. A recent study investigated parental education as a moderator of genetic and environmental effects on verbal and nonverbal cognitive abilities in a German sample of young twins (Spengler et al, 2018). This study only revealed a significant nonshared environmental x parental education interaction for verbal abilities.…”

Genetic and Environmental Influences on Verbal Aspects of Twins

“…Rosalind et al, (2018) reported that cognitive abilities of twins were heritable and observed that the genetic and environmental influences on different developmental patterns of verbal and non-verbal cognitive abilities of twins from the age group 7 to 12 years. Spengler et al, (2018) investigated that genetic and environmental effects on verbal cognitive abilities of twins in the age of 7-14 years and reported that verbal cognitive ability and nonverbal ability indicated no significant interaction with parental education, while verbal abilities showed a significant interaction with parental education. The verbal abilities were more influenced by genetic factors.…”