It has been consistently found that individual differences in beliefs, value priorities, and attitudes are due to both environmental and genetic influences. In this study, we investigated the effects of nature and nurture on... [ view full abstract ]
It has been consistently found that individual differences in beliefs, value priorities, and attitudes are due to both environmental and genetic influences. In this study, we investigated the effects of nature and nurture on individual differences in five universally observable but differently developed moral intuitions: Harm/Care (i.e., avoiding harm to others), Fairness/Reciprocity (i.e., doing the right things to ensure fair treatment for all), Ingroup/Loyalty (i.e., having a system that protects the social institutions of family, community, and country), Authority/Respect (i.e., complying with duty, authorities, laws, and tradition), and Purity/Sanctity (i.e., preferring religious norms, decency, and maintaining purity of mind).
Data from 546 twins (102 monozygotic and 171 dizygotic twin pairs) who already participated in the ongoing Study of Personality Architecture and Dynamics (www.speady.de) were analyzed. We estimated genetic and environmental sources of individual differences in moral intuitions using a latent variable approach to control for error of measurement.
The results indicate that individual differences in Harm/Care and Fairness/Reciprocity were primarily due to genetic influences (76% and 44%) and individual-specific environmental factors (21% and 50%), whereas variance in Ingroup/Loyalty and Authority/Respect was primarily attributable to environmental influences shared (26% and 33%) and not shared by twins (62% and 67%). Purity/Sanctity showed significant genetic (22%) and shared (33%) as well as nonshared environmental (45%) variance components. Genetically informative common factor analyses indicated that a common factor of Harm/Care, Fairness/Reciprocity, and Ingroup/Loyalty mediated most of the genetic variance in these variables, whereas a common factor of Ingroup/Loyalty, Authority/Respect, and Purity/Sanctity mediated most of their shared environmental variance components. These results will be discussed against the background of the structure and theory of moral foundations and related constructs, such as value priorities and political attitudes.
(The authors received support from the Deutsche Forschungsgemeinschaft KA 4088/2-1)
