Sources of Differences in Right-Wing Authoritarianism and Social Dominance Orientation from Adolescence to Adulthood: A Multi-Cohort Twin Family Study

Past research indicates that both genetic and environmental sources contribute to two core dimensions of individual differences in socio-political attitudes: Right-Wing Authoritarianism (RWA) and Social Dominance Orientation (SDO). However, less is known about differences between the sources of variance in RWA and SDO, and how these sources vary by age. Based on data from 1440 twin families including 1198 complete twin pairs, 435 non-twin full siblings, and 2016 parents of twins from the German TwinLife project, nuclear twin family modeling (NTFM) was used to estimate different genetic and environmental variance components of RWA and SDO, and to examine the extent to which the variance components vary across three age cohorts of twins (average age 15, 21, and 27 years). We hypothesized increasing levels of genetic differences across age cohorts, reflecting more active genotype-environment transactions with development, and declining levels of passive genotype-environment correlation. The results showed some differences regarding the sources of variance in RWA and SDO. RWA showed stronger environmental effects shared in families due to intergenerational non-genetic transmission from parents to offspring, and both passive genotype-environment covariance and additive genetic variance declined across cohorts, while nonadditive genetic differences increased. For SDO, passive genotype-environment covariance components were generally negligible, while additive genetic variance components tended to increase across cohorts. These findings were only partially consistent with our expectations. Counterintuitively, the influence of within-familial environmental factors on RWA were larger in adulthood than adolescence. The results are discussed against a background of developmental theories and potential cohort differences.