There is actually a clever way of answering questions like these: by studying fraternal and identical twins, a technique psychologists often use to determine whether some personality trait is innate or a product of the environment. A new paper (paywall) on a group of around 1,200 adult twins born in Minnesota concludes that to a surprising degree, our politics do not depend on our circumstances. Rather, they are partly determined at conception, encoded in the nucleus of every cell in our bodies.
The researchers found that two identical twins are likely to respond in very similar ways to questions about politics and ideology. A pair of fraternal twins are, by comparison, more likely to give different responses.
What could explain the disparity? Both members of a pair of twins are raised in the same household, and while they may have different relationships with their parents or different kinds of experiences at school, these differences are presumably no greater for fraternal twins than for identical twins.
Genes are the most likely explanation for the different ways the two groups of twins responded to the questions, since fraternal twins share less of their genetic material than identical twins.
What's even more surprising is that the twins the researchers surveyed were between 52 and 62 years old. They had had several decades in which to question their parents, pursue a career, and raise children of their own. After all that time, pairs of identical twins still had more similar politics than pairs of fraternal twins.
The authors of the paper are affiliated with several universities and were led by Cary Funk, who is now at the Pew Research Center.
The researchers attributed more than half of the variation in the ideology of their subjects to genetic factors -- although it is important to note that the twins in the study were "middle-aged, overwhelmingly white, and geographically concentrated in the Midwest," the authors wrote. More cultural diversity among the twins might have led to larger differences in their political views that genetic factors alone could not explain.
These results will not be surprising for psychologists, who have long said that we can inherit the kinds of personality traits that are associated with a particular political orientation. A couple of years ago, another group tried to identify the specific regions of the genome that might be responsible for transmitting political views from generation to generation. More recently, New York University psychologist Jonathan Haidt has developed a schema to explain our different emotional responses to moral problems, which he argues can account for the deep hatred people of different political inclinations can feel for one another.
There are, of course, any number of factors that determine why we believe what we believe, including our own ability to weigh arguments and make decisions -- although if you spend too much time thinking about how that ability is also affected by cultural and biological factors, you'll quickly run up against some very difficult and very old philosophical questions. Our views aren't completely determined by our heredity, as is clear from the fact that public opinion can shift suddenly and dramatically on an issue, like gay marriage.
Still, the study of twins born in Minnesota is interesting because it shows convincingly just how influential genes are in crafting our baseline political views. And maybe, this kind of research will make us more tolerant of those who see the world differently from ourselves. It's not entirely their fault they're wrong.