Genetic & environmental sources of individual differences in homophobic tendencies towards gay men: A large proportion of genetic factors (82%) contribute to individual differences in homophobia

Sources of Individual Differences in Sociopolitical Orientations: Findings from Combining Behavior Genetic with Multi-Rater Approaches. Alexandra Zapko-Willmes. Kumulative Dissertation zur Erlangung des akademischen Grades Dr. rer. nat. im Fach Psychologie, Universität Bielefeld. Oct 2018. http://pub.uni-bielefeld.de/download/29325

Summary
In the three studies constituting this dissertation, behavior genetic and multi-rater approaches were combined to contribute to the understanding of sources of interindividual differences in broad and narrow dimensions of sociopolitical orientations. For this purpose, all studies employed structural equation modeling designs based on cross-sectional twin family and multi-rater data from the Jena Twin Study of Social Attitudes (JeTSSA; studies 1 and 2) and the Study of Personality Architecture and Dynamics (SPeADy; study 3).

Study 1 was aimed at validating and extending previous self-report studies on genetic and environmental sources of individual differences in homophobic tendencies towards gay men across multiple rater perspectives. In line with our hypotheses, we found a large proportion of genetic factors (82%) to contribute to individual differences in homophobia, with unique environmental factors (18%) explaining the remaining variance. Moreover, we found variance specific for self-reports to be partially attributable to genetic factors (20%), confirming past findings that suggested that self-reports may underlie genetic influences. Results indicate the importance of univariate behavior genetic investigations.

Study 2 was conducted to examine, whether differences in experienced parenting affect present differences in twin sibling’s right-wing authoritarianism (RWA) via a “truly” environmental pathway as opposed to a genetic mediation. We integrated genetically informed and phenotypic multi-rater models to investigate whether and how the association is confounded due to shared genetic and environmental sources of both variables. We considered offspring’s, mothers’, and fathers’ retrospective ratings of two parenting dimensions and offspring’s self- and informant reports on their RWA. Our hypotheses were generally not confirmed. An evocative genotype-environment correlation likely explained the positive link between parental responsiveness and differences in offspring’s RWA. In other words, the offspring’s genetically influenced RWA score (and associated behavior) affected their experienced parental emotional warmth and support, with a higher RWA score associated with more highly experienced responsiveness. In contrast, we found an effectively environmental positive association between differences in experienced parental demandingness and differences in twin sibling’s RWA. Parental RWA, while not associated with parental responsiveness, partly explained the link between experienced demandingness and differences in offspring’s RWA.  Findings underlined the additional insight gained through multiple raters on the environmental as well as characteristic.

Finally, study 3 examined the convergence of basic value orientations and foci of moral concern as two abstract dimensions of sociopolitical orientations. We expected the dimensions to converge based on common underlying world beliefs. The value orientation towards conservation versus openness to change was expected to converge with a moral focus on organization versus opportunity due to the underlying belief in a dangerous world. The value orientation self-transcendence versus self-enhancement was expected to converge with a moral focus on social versus individual outcomes due to the underlying (lack of) belief in a competitive world. We combined multi-rater with twin family data to investigate four criteria of convergence (structural, age-related, source-related, and the link with a key personality trait). For both expected links, we found the dimensions to be systematically linked, but reflect distinct characteristics, suggesting that they reflect characteristics of different personality layers. We discussed the role of specific motives and environmental factors contributing to differences in foci of moral concern.


Introduction
According to an old saying and etiquette rule1, one should avoid conversations about political topics, alluding to the inevitably ensuing disputes fueled by individual differences in social and political views. When viewed through historic and current events, these interindividual differences may have major individual-level, group-level, societal, and even global consequences beyond mere heated disputes. Individual preferences regarding social and political issues, subsumed under the term sociopolitical orientations, have been linked to various forms of prejudice (Altemeyer, 1996; Asbrock, Sibley, & Duckitt, 2010; Duckitt & Farre, 1994; Ekehammar, Akrami, Gylje, & Zakrisson, 2004; Hodson & Dhont, 2015), support for radical right parties (Aichholzer & Zandonella, 2016; Cornelis & Van Hiel, 2015; but see also Dunn, 2015), endorsement of human rights and associated behavior (Cohrs, Maes, Moschner, & Kielmann, 2007), and post-9/11 attitudes (Crowson, DeBacker, & Thoma, 2005, 2006), to name a few. Furthermore, its impact could be recently observed in the context of political participation and voting behavior in the Brexit referendum (Golec de Zavala, Guerra, & Simão, 2017) as well as the US presidential election (Choma & Hanoch, 2017; Womick, Rothmund, Azevedo, King, & Jost, 2018).

These findings corroborate the importance of research on the factors that contribute to individual differences in sociopolitical orientations. An important piece of this puzzle is the identification of the biological and environmental roots of these characteristics. These roots have long been regarded as being essentially – even exclusively – environmental; Genetic explanations were largely disregarded in favor of socialization explanations (e.g., Adorno, Frenkel-Brunswik, Levinson, & Sanford, 1950; Altemeyer, 1988). However, behavior genetic studies (e.g., Eaves & Eysenck, 1974; Eaves et al., 1999; Kandler, Bleidorn, & Riemann, 2012; Martin et al., 1986) have shown that environmental factors shared between twin siblings (which would reflect a large portion of the argued socialization) are not as crucial as previously assumed, and that genetic and idiosyncratic environmental effects are substantial. After decades of neglecting genetic explanations, there is no longer a “nature versus nurture” debate when it comes to sources of individual differences in sociopolitical orientations, as well as other personality characteristics2 and virtually all complex human dispositions (Polderman et al., 2015). Rather, nature and nurture are agreed to be interwoven with each other (Plomin, DeFries, & Loehlin, 1977; Scarr & McCartney, 1983). 

In this work, I sought to contribute to the understanding of the sources of interindividual differences in sociopolitical orientations. Sociopolitical orientations were studied at various levels of content-related abstraction (Section I), ranging from specific dimensions (i.e., homophobia; study 1), to broad, less specific dimensions that capture individual global social and political preferences (i.e., right-wing authoritarianism; study 2) to even more abstract motivational and affective-cognitive dimensions (i.e., value orientations and foci of moral concern; study 3). I employed both behavior genetic and multi-rater models to overcome methodological limitations (Section II) of past univariate (study 1) and multivariate (study 2) behavior genetic research, and to gain insight into the convergence of two conceptually related dimensions of sociopolitical orientations (study 3).