Self-control and grit are associated with school performance mainly because of shared genetic effects

Abstract

Background: By combining the classical twin design with regression analysis, we investigated the role of two non-cognitive factors, self-control and grit, in the prediction of school performance. We did so at the phenotypic, genetic, and environmental level. Methods: Teachers filled out a survey on the twins’ school performance (school grades for reading, literacy, and math), self-control (ASEBA self-control scale), and grit (the perseverance aspect) for 4,891 Dutch 12-years-old twin pairs (3,837 pairs with data for both and 1,054 pairs with data for one of the twins). We employed regression analyses to first assess the contributions of self-control and grit to school performance at the phenotypic level, and next at the genetic and environmental level, while correcting for rater (teacher) effects, parental SES, and sex. Results: Higher SES was associated with better school performance, self-control, and grit. On average, girls had more self-control and grit than boys. Corrected for sex, SES, and teacher rater effects, genetic factors accounted for 74%, 69%, and 58% of the phenotypic variance of school performance, self-control, and grit, respectively. Phenotypically, self-control and grit explained 28.3% of the variance in school performance. We found that this phenotypic result largely reflected genetic influences. Conclusions: Children who have better self-control and are grittier tend to do better in school. Individual differences in these three traits are not correlated because of shared environmental influences, but mainly because of shared genetic factors.

Intergenerational transmission of education and mental health

“…cognitive skills or intelligence), as measured by cognitive tests. Cognitive performance is known to be correlated to educational achievement and attainment between 0.4 and 0.8 [17][18][19][20] , sharing large overlapping genetic influences (genetic correlations ~ 0.7) [21][22][23] . Though it should be noted the relation between cognition and education is likely bidirectional 24 , higher cognitive performance increases educational opportunities.…”

Genetically informed analyses of childhood individual differences

“…As reported in Kevenaar et al (2023), we previously analysed teacher ratings of grit, self-control, and school performance in MZ and DZ twins using the same data that were analysed for the present article. The results were obtained with a correction for the main effects of sex and SES, and a correction for the rater (i.e., the teacher of the twins).…”

“…In a twin study, Kevenaar et al (2023) found that grit and self-control together explained 28.4% of the variance in school performance. The decomposition of the phenotypic regression relationships into genetic and environmental components revealed that the phenotypic associations were mainly due to genetic factors.…”

“…Our present aim is to contribute to the causal research by following up the analyses of Kevenaar et al (2023). The classical twin design provides the means to estimate the phenotypic relationship between the non-cognitive factors and school performance while accounting for the genetic background correlation between these variables (Kohler, Behrman & Schnittker, 2011).…”

“…The outline of this article is as follows. First, we introduce the twin model and provide a summary of the results of Kevenaar et al (2023). Next, we present a causal twin model, which we apply to explore the putative causal influence of grit and self-control and school performance.…”