When I studied abroad last fall in Stockholm, Sweden, I took a course called Psychology of Political Behavior. It was honestly one of the best, most mind-blowing, perception-of-the-world-altering classes I’ve ever taken, and since I’m one of few who has had the chance to take that class, I thought I’d share some of what I learned for my first blog post! We covered so many different topics from all areas of political psychology but one of the most interesting (and relevant for this blog about psychology and neuroscience) lectures was about how biological factors like genes and neuroanatomy are interconnected to influence our personality traits and political opinions. (I’m going to preface by saying that this is an extremely complex, controversial and largely under-understood area of research and I know I’ll only be able to address a tiny fraction of it in this post.)

I want to start out by discussing research that has shown that genetics plays a factor in our political beliefs. Some of the most convincing evidence has come from twin-studies. Identical twins share nearly identical genetic material, while fraternal twins only share, on average, fifty percent of their genes. Since twins are almost always raised in the same environment, with the same parents, schools, religion, community, etc., twin studies are generally seen as a way to determine how much of an influence genetics plays on any given trait. By analyzing the differences between twins in each pair, and then comparing fraternal and identical pairs, you can estimate how much of those differences are influenced by genes and how much variation comes from other factors. Twin studies have shown that genetics plays a strong role in determining political ideology and behavior. For example, Funk et al. looked at a variety of political attitudes and found that 56% of the differences in self-identified political ideology, 48% of authoritarian beliefs, 54% of ideas about social organization were explained by genetic factors. Another study also found that between 40 and 60% of the differences in voting turnout between twin types came from genetics. Genetics likely has a stronger impact that we realize on political beliefs and behaviors.

Another biological factor that has been shown to be correlated with different political opinions is the size of various brain regions. While this is a controversial area of research, multiple studies have shown converging evidence that the brains of conservatives and liberals are structurally different in a few important ways. The amygdala is a region of the brain that is associated with motivation and emotions such as fear and anxiety. Increased grey matter volume in the right amygdala was shown to be correlated with conservatism. Additionally, higher grey matter volumes in the anterior cingulate cortex (ACC), an area of the brain that has a variety of different functions including error detection, emotion regulation, and cognitive control, were associated with liberalism. It is important to note, however, that these studies show correlation not causation, and that it is difficult to determine whether these differences are there at birth and lead a person to join one political party or another, or if the fact that a person identifies with a particular party then leads to brain differences over time.

Ok. So. What does this all mean? It is easy to get caught up in thinking that results like these mean that we could use brain scans or DNA sequencing at the polls to determine voters’ political beliefs. Instead, we must tread carefully when evaluating the findings of these types of studies. First, I want to point out that, of course, no specific ‘genes for liberalism’ or ‘genes for conservatism’ have yet been identified, and it is likely that there is a complex interaction between many genes to influence party identity. Saying that genetics plays a role in determining our political ideologies and behaviors does not mean that the DNA sequence of a person automatically predetermines that they will absolutely grow up to have certain beliefs. Instead, genes might work to influence the size of various brain areas and how one’s brain is wired.

These differences in genes and brain anatomy can then contribute to differences in personality traits. For example, the twin study mentioned previously also looked at the “Big Five” personality traits and found that at 70% of extroversion, 43% of openness to experience and 42% of neuroticism was genetically linked. Conservatives have also been found, in general, to score higher on neuroticism and lower on openness than liberals, suggesting a further genetic influence on politics. Then it follows that, based on differences in personality traits arising from differences in biology, people will seek out and expose themselves to different experiences, people, and ideas (for example, someone higher in ‘openness’ might be more likely to move to a city, try new things, travel, and meet lots of different people). This then pushes them further down the path towards one political affiliation or another. Thus, genes influence neuroanatomy which influences personality traits which influences life experiences which ultimately all combine to shape one’s politics. This isn’t to say that a person’s genes definitively will result in them having a specific political belief, but more that factors like genes, neuroanatomy and personality can tend to nudge someone, through the experiences they then choose throughout their lives, towards one or another.

I’ve only scratched the surface of this complex issue and there are many other genetic correlations, brain areas, and personality traits that could have been discussed in this post, but I hope I’ve provided you with a basic understanding of how biology can influence the psychology of politics. With all this in mind, I want to leave you with one final thought; the next time you get into an argument over politics with a person who might have different ideas than you, just keep in mind that differences in genes and neuroanatomy (which might have then led to different personality traits and experiences) might have contributed to their stance on whatever issue you’re disagreeing about.