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.