Heritability of Justice Sensitivity

Abstract. Justice is one of the fundamental principles in human evolution, and justice sensitivity from the pro-self (e.g., as a victim) and the prosocial perspective (e.g., as an observer, beneficiary, and perpetrator) matters in mental wellness and social interaction. However, the extent to which individual difference in justice sensitivity is influenced by genetic versus environmental factors remains unclear. Using a sample with 244 twin pairs, the present research attempts to determine the extent to which genetic factors play a role in the inter-individual difference of justice sensitivity as well as whether different facets of justice sensitivity, namely, pro-self and prosocial perspectives, share a common genetic basis. Results showed that (1) all facets of justice sensitivity were moderately heritable (21–33%) and that the non-shared environmental factors plus measurement error accounted for the rest of the variations (67–79%); (2) associations between the prosocial facets of justice sensitivity were driven by common genetic ( rg = .50–.65) and non-shared environmental (plus measurement error; re = .24–.65) influences, whereas no significant genetic link was found between the pro-self and prosocial facets. The current findings provide novel evidence that sensitivity to injustice, especially to others’ suffering, is fundamentally grounded upon genetic origin, thereby shedding light on the nature and nurture aspects of justice behavior.