Neuroanatomical work provides partial support for functional imaging findings linking political conservatism to the ACC and amygdala. For instance, Kanai et al. (2011) recently reported that increased grey matter volume in the ACC and decreased volume of the right amygdala predicts political liberalism in young adults. This association between liberalism and the ACC supports the work noted above forging links between politics and conflict monitoring/response. And the finding that liberals have less grey matter in the amygdala – a region with links to disgust processing and fear conditioning – also converges with behavioural work showing that conservatives tend to be more disgust sensitive and responsive to threat (Oxley et al., 2008).
Lewis, G. J. and Bates, T. C. (2013). The long reach of the gene: Prejudice, politics, and religiosity. The Psychologist, 26. 194-199. (pdf)
One does not have to look very hard to observe that people differ greatly in their social and political attitudes. Views on religion, gun control, free markets, and political parties can divide rooms. But from where do these differences in opinion emerge? And what do genes and biology have to do with this apparently most social of questions?
This essay describes a growing body of work suggesting that our biological makeup influences our social and political attitudes and explores the methods that underpin such claims. The authors argue that the conclusions from this work are increasingly clear: understanding political divides will require biological as well as social explanations.
[. . .] It will come as no news that people differ, often strikingly, in their views on how society should be run. Whereas some value ethnic diversity, others believe non-indigenous individuals should be repatriated to their land of origin, as demonstrated in the views of the antiimmigration British National Party. And while some feel religion ought to play no role in government, others strongly advocate God’s law as national law, such as those who support a strict interpretation of Sharia. While these facts are clear to all, the origins of these individual differences in social attitudes remain ill understood, despite having been of enduring interest to psychologists, sociologists, and political scientists. This is unfortunate as one only need bring to mind the shocking terrorist attacks of 7/7 and 9/11 to recognise that attitudes and values can have very real consequences for human lives.
While work in this area has almost exclusively focused on environmental determinants of social and political sentiment, recent evidence strongly implicates a role for genetic factors. In this article we introduce this behaviour genetic approach for understanding aetiologies of social attitudes: one that has been gaining momentum in recent years. We highlight some core as well as recent results in the literature, examine some of the challenges currently facing the field, and investigate possible future paths of research. Before tackling these issues, however, we start with a brief introduction to behaviour genetic methods. [. . .]
Genetic insights into social and political attitudes
The earliest genetically informative study of socio-political attitudes was conducted by Eaves and Eysenck (1974), who found that self-reported radicalism (vs. conservatism) and tough-mindedness (vs. tender-mindedness) were both substantially influenced by heritable factors. However, these heterodox findings were not widely cited in the literature (despite being published in Nature). This appears to have been due in large part to extended criticisms of genetic explanations of social behaviour and attitudes: biological explanations at this time were simply not in vogue (Segerstråle, 2000).
Some 12 years later a second such article appeared (Martin et al., 1986), replicating the findings of Eaves and Eysenck (1974), and extending the scope of heritable influences on social and political attitudes to include a broader range of social and political issues, including gay rights, the death penalty and abortion. These findings too, however, largely failed to enter mainstream consideration of these results until being revisited in 2005 by political scientist John Alford and colleagues, who presented reanalyses of these data to a wide and influential social and political science audience.
Subsequently, a growing stream of findings has emerged into the literature, replicating and extending these initial findings of genetic influence on social and political attitudes. For instance, Hatemi et al. (2009) found that genetic effects on political attitudes emerge strongly only after children have typically left the family home, with MZ twins converging and DZ twins diverging in similarity around young adulthood (> 20 years of age). And Fowler et al. (2008) observed that the decision to vote at all (voter turnout) is substantially heritable; indeed, more so than partychoice or political attitudes.
[. . .] Recently, we ourselves examined the heritable basis of religiosity (Lewis & Bates, 2012b). We again found that religiosity was heritable, but perhaps more interesting was the observation that these heritable influences on religiosity were completely accounted for by genetic influences on traits with no intrinsic religious component; namely, basic sentiment concerning community integration and existential certainty.
Unlike politics and religion, the genetic basis of in-group favouritism and prejudice had not been studied at all until recently. Work from our own group demonstrated that in-group favouritism also contains a substantial heritable component (Lewis & Bates, 2010). In this study, we examined the claim that race favouritism (i.e. preferences for members of one’s own racial group) is simply one manifestation of a more general ‘us vs. them’ coalitional mechanism. This claim is based on reasoning that limited exposure to other racial groups over evolutionary time necessarily must have limited any ability of natural selection to shape the human mind towards specific race preferences (Kurzban et al., 2001). Our study found support for a common, and strongly heritable, favouritism ‘system’ – reflecting in-group bias in the realm of religion, ethnicity and race. Interestingly, however, we also found evidence for specific sets of genetic factors for each of these forms of favouritism: in other words, even when one accounts for the common favouritism system, additional genetic factors appear to influence race favouritism.
The overarching sentiments emerging from these genetic studies of attitudes are twofold. Firstly, genetic influences are evident on a range of social and political traits and behaviours, an observation that sits in contrast to common assumptions in social sciences, although one that should not be ignored if we are to fully unravel the origins of social attitudes. Secondly, genetic architectures of social traits are likely to be both complex and multifaceted, as evidenced, for example, by the multiple heritable influences underlying in-group favouritism (Lewis & Bates, 2010). [. . . ]
What mechanisms mediate the pathway?
Even if molecular markers cannot be easily located, knowledge that genetic factors are at work in shaping social attitudes gives rise to a key question: Through what neurobiological systems do these genetic effects manifest their influence? Although work of this kind is largely in its infancy, some encouraging results have been reported in recent years, representing both neuroanatomical and functional imaging associations with social and political attitudes. Amodio et al. (2007) reported an association between political conservatism and conflict-related activity during a Go/No- Go task using event-related potentials. The Go/No-go task requires participants to make a response (‘go’), or to withhold a response (‘no-go’), to specific stimuli, with go trials typically occurring with higher frequency than the irregular no-go trials, which are believed to engage conflicting monitoring systems. Interestingly, the neural activity reported in this study originated in, or near, the anterior cingulate cortex (ACC), a region with known links to conflict monitoring. The authors interpreted this finding as evidence that liberals possess ‘greater neurocognitive sensitivity to cues for altering a habitual response pattern’ (p.1246). More recently, Inzlicht et al. (2009) supported this association between conservatism/traditionalism and ACC function, finding that greater religious belief – which itself is commonly linked with conservatism – was associated with decreased activity in the ACC following errors in a Stroop task. In this paper, however, the authors suggest that rather than ACC activity influencing subsequent traditional attitudes (as suggested by Amodio et al., 2007), decreased ACC activity reflects the fact that ‘religious conviction buffers against anxiety by providing meaning systems’ (p.390), although they noted that establishing direction of causation requires further experimentation.
Neuroanatomical work provides partial support for functional imaging findings linking political conservatism to the ACC and amygdala. For instance, Kanai et al. (2011) recently reported that increased grey matter volume in the ACC and decreased volume of the right amygdala predicts political liberalism in young adults. This association between liberalism and the ACC supports the work noted above forging links between politics and conflict monitoring/response. And the finding that liberals have less grey matter in the amygdala – a region with links to disgust processing and fear conditioning – also converges with behavioural work showing that conservatives tend to be more disgust sensitive and responsive to threat (Oxley et al., 2008). Following on from this work, Lewis and colleagues (2012) found that moral concerns with (1) limiting harm to others and maximising fairness, and (2) authority deference, group loyalty, and purity/sanctity were associated with grey matter volume in dorsomedial prefrontal cortex and subcallosal gyrus, respectively. While subcallosal gyrus had not been implicated in social attitudes previously, dorsomedial prefrontal cortex is a major hub facilitating social cognition and mentalising (Amodio & Frith, 2006), thus supporting links between this region and concerns over others well-being.
Taken together, these findings begin to lay the foundations for detailed understandings of how genetic factors modulate neurobiology, and in turn generate individual differences in social attitudes. What is not yet understood, however, is whether these brain regions are linked to social attitudes via genetic pathways or environmentally influenced pathways. We are only at the very beginning of the quest to answer such questions; however, social psychological work combining the powerful methods of genetics with cognitive neuroscience techniques (e.g. Toga & Thompson, 2005) may lead to powerful insights into the biological mechanisms that underpin social attitudes.
Mutability of genetic effects
One of the perennial concerns levelled at work purporting to find a genetic basis to traits of central interest to human existence, as social and political attitudes clearly are, is that they suggest determinism and immutable effects. While this criticism is itself often rather ideologically predictable (i.e. criticisms seem directed more frequently when the findings appear to conflict with values), it is certainly true that such immutability, at least in the case of social attitudes, seems to be quite the opposite of what we see around us much of the time: as Winston Churchill noted, ‘If you’re not a liberal at twenty you have no heart, if you’re not a conservative at forty you have no brain’, alluding to the notion that context plays an important role in the expression of political attitudes.
Leaving aside the political wrangling, what is clear here is that political affiliations do change, and sometimes markedly. How can genetic studies account for such observations? One answer to this question is that genetic influences on social and political attitudes are unlikely to reflect mechanisms designed to output focal behaviours such as joining specific political parties (e.g. Labour or Conservative), or believing in a specific divine figure: indeed, twin studies show that while strength of religious belief is heritable, the actual denomination one ascribes to is almost entirely attributable to environmental influences (D’Onofrio et al., 1999). Rather, it is more probable that these underlying genetic influences serve to shape somewhat less focal social behaviours, such as general concerns for norm adherence. In support of this notion, interesting recent work by Duckitt and Sibley (2010) suggests prejudice, at least in part, may reflect increased concerns over violations of social norms: out-groups who are perceived as breaking local norms are typically most disliked. We recently tested this hypothesis using a twin sample and found that genetic factors influencing prejudice were substantially overlapping with measures of traditionalism and rightwing authoritarianism (Lewis & Bates, 2012a), both of which are measures reflecting concerns for norm maintenance. It is plausible, then, that mean levels of prejudice are moderated by environmental factors – such as realistic challenges to social norms – but that individual responses to these challenges reflect underlying heritable sensitivities to norm violations. [. . .]