HERITABILITY FOR SOCIAL TRUST ACROSS SOCIOECONOMIC STATUS: : Is There a Gene-Environment Interaction?

Abstract: In political science literature, the development of social trust is often explained in terms of the influence of different environmental factors, socioeconomic status (SES) being one of the most important. Yet, even though there is empirical support of a genetic component in the expression of social trust, less is known about its interaction with environmental factors. The present study aims to explore heritability of social trust across socioeconomic status using a twin-design that tests potential gene-environment (GxE) interactions. Moreover, the study explicitly tests the hypothesis that different levels of SES may moderate the influence of genetic and environmental effects on social trust. Data comes from the Swedish Twin Registry and consist of 1535 twin pairs born between 1943–1959. Social trust was measured through self-report on a scale of 1–10. Socioeconomic status was assessed as a dichotomized variable of high/low SES, determined on the basis of the father’s occupation during the twin’s childhood or adolescence. To test whether SES interacted with genetic and environmental effects for social trust, I used structural equation modeling (SEM). Results from the best fitting model show that social trust has a significant genetic component, with an estimated heritability of 0.41 in low SES and 0.33 in high SES. Results showed no evidence for a significant difference in heritability between low and high SES. Accordingly, it can be concluded that the results of the study do not support the hypothesis that SES moderate the influence of genetic effects on social trust.