This post is part of an ongoing series concerning the level of conscious control humans have over their political thoughts and decisions.
It would be silly to think of newborn babies’ brains as being a blank slate. The preponderance of biological research has shown that differences in our genes play a large role in our personality. But certainly our political opinions are formed some time after we’re born, since we need some actual political information before we can develop political attitudes, right?
Well, kinda.
Numerous studies have shown that monozygotic (identical) twins are more likely than dizygotic (fraternal) twins to hold similar political opinions and exhibit similar political behaviors, showing that our genes play a role in determining what our political opinions are, how strongly we hold them and even whether or not we decide to vote.

Twins via Shutterstock.
What’s important to note, as is the case with all twin studies, is that comparing identical to fraternal twins controls for the “shared household” objection. It’s natural to assume that twins, or siblings, will share political attitudes because they grow up in the same house in the same geographic area with the same parents telling them what to think. But when identical twins, with matching genes, are more alike than fraternal twins, who only share 50% of each others’ genes, the difference between the two can be attributed to genetic difference.
So, while this is not to say that our political opinions are 100% set when we’re born, nature provides a robust “first draft,” or cognitive structure, which we use to process information and which helps construct our political attitudes as we mature. It is perhaps for this reason that studies examining this phenomenon have consistently found that genes play a significant role in the ideologies we hold, but not the parties we identify with. The former is internal and value-based; the latter is an external and artificial construction – far more prone to environmental manipulation.
So while there isn’t a “Democrat Gene” or a “Republican Gene,” there are genes for which variations can predispose someone to be more liberal or conservative.
For example, those who are predisposed to greater levels of fear and risk-aversion are more likely to be conservative, even to the point of exhibiting varying physical responses in laboratory settings. Furthermore, it has been shown that conservatives have a larger amygdala than liberals, which could explain why these differences are found (the amygdala is active during states of fear and anxiety).
Furthermore, even though a genetic link for partisan affiliation itself has not been established, a link between partisanship itself (in either direction) and the propensity to engage in collective action has.
Over the course of primate evolution, it has become evolutionarily advantageous to engage in collective action. I help you protect your stuff (instead of killing you and taking it), with the expectation that you will do the same for me down the road. In entering into this agreement, we are both able to acquire more, reduce risk and, as a result, have more children and prosper. In this way, selective pressure to act collectively arose over time, creating a human race that is, at its core, social.
But inherent differences in our propensity to act collectively exist, and these differences can be borne out in strength of partisan affiliation (an exercise in collective action). Those who are more likely to donate money or volunteer for a political campaign are, because they are predisposed to in-group behavior, more likely to cooperate for the purpose of solving other collective action problems.
As we’ll see, there are plenty of other environmental factors that contribute to our attitudes and decisions. But no conversation about behavior can start at anywhere other than a genetic level. Having established that genes play a significant role in political behavior, we can move on to environmental factors in subsequent posts.
