Nature Versus Nurture.

Okay, take a deep breath for this one: we are not blank slates, and that's okay.

Meet my friends Eddie, Freddie, Dan, and Mark. Eddie and Freddie are monozygotic — or identical — twins. They share everything with each other, including 100% of their DNA. Dan and Mark are dizygotic — or fraternal — twins. They, too, share a great deal with one another, but only share 50% of their DNA, which is the same amount any non-twin siblings would also share.

"Hold on, hold on. I thought this was an article about political orientation? What the hell do twins have to do with political orientation? Our political stances are based on ideology, not biology." Well, yes and no. While the ideologies that underlie our political stances must undoubtedly reflect our sociopolitical preferences, how these preferences develop is another matter entirely.

What Twin Studies Reveal

Let's get back to our pals the twins, shall we? Looking at the differences that emerge between monozygotic and dizygotic twins is arguably the gold standard of testing nature versus nurture claims. Because Eddie and Freddie share 100% of their "genetic code," any differences that emerge between them can likely be attributed to environmental influence. Let's take political orientation, for example. Will Eddie and Freddie (who share all of their DNA) tend to have more similar political outlooks than their less genetically-related brethren, Dan and Mark (who only share half of their DNA)? Indeed they will (Eaves & Eysenck, 1974). In fact, not only will the political attitudes of Eddie and Freddie correlate more strongly with one another than Dan and Mark if both pairs are raised under the same roof, but the political orientations of the former duo will continue to be significantly correlated even if they are raised in separate environments (Waller, Kojetin, Bouchard, Lykken, & Tellegen, 1990). The same, however, cannot be said for Dan and Mark.

"Wait! But I know a set of fraternal twins who are both Republicans and a set of identical twins where one is a Republican and one is a Democrat!" That's certainly possible. The studies above (along with many others) do not suggest that some sets of fraternal twins can't have political orientations that are closer to one another than some sets of identical twins, they just note that these results are possible but not probable (a distinction we'll delve into in a bit more detail later). For instance, just because men as a group tend to be physically stronger than women as a group doesn't mean there won't be examples of individual women who are stronger than individual men — the probability is just simply not in their favor. This type of argument (from the first sentence of this paragraph) is tantamount to denying that global warming exists because today is cold. Here, a singular example is used as an attempt to disregard or discredit a compendium of robust statistical data. This type of logical fallacy is often referred to as "cherry picking," and falls under the subcategory of faulty generalizations.

Personality At Age Three Predicts Political Orientation At Twenty

Further corroborating the evidence of the genetic heritability of political predispositions are Jeanne and Jack Block. In one of the longest longitudinal studies on political development ever conducted (Block & Block, 2006), the Block's measured the personality traits of over 100 children at age three and again at four, and then tracked their political trajectory for more than 20 years. The young children were assessed by six independent teachers (three at the age of three and three new ones again at the age of four), each of whom interacted with the child on a daily basis for a minimum of seven months. Twenty years later, children whose preschool assessments described them as "expressive, autonomous, curious, and relatively under-controlled" were overwhelmingly liberal, while those that described them as "neat, compliant, uncomfortable with uncertainty, rigidifying when under duress, and relatively over-controlled" were overwhelmingly conservative.

These findings are quite remarkable. These children were three and four years old; long before they possessed the capacity or opportunity (or interest) to deliberate over the relative merits of political liberalism versus political conservatism. And yet it seems as though some of them were already predisposed (note: not "destined") to gravitate toward one political orientation over the other. By simply examining several personality dimensions of these preschool children, we could predict — at a rate much greater than chance — which end of the political spectrum they'd find themselves on as young adults.

Neural Differences Between Liberals And Conservatives

There appear to be neural differences between individuals on opposite ends of the political spectrum, as well. In experiments conducted at University College London (Kanai, Feilden, Firth, & Rees, 2011), researchers were able to identify two neural structures that differ in size and composition in self-described liberals and conservatives. Liberals tended to have more gray matter in their anterior cingulate cortex — a neural region often implicated in processes involving empathy — whereas conservatives had a larger right amygdala — an area of the brain critical to vigilance and primal emotions such as fear. In fact, the neural differences were so pronounced that simply by having access to the measurements of these two brain areas (and nothing else) would enable you to accurately identify someone's political orientation with approximately 72% accuracy.

Overall, scientists typically agree that about 40 to 60 percent of the variability in our political attitudes can be attributed to genetic differences (Alford & Hibbing, 2004; Hatemi, Medland, Klemmensen, Oskarsson, Littvay, Dawes, et al., 2013; Martin, Eaves, Heath, Jardine, Feingold, & Eysenck, 1986). If genetics didn't play a role, then adoptive siblings raised in the same environment would be just as similar as biological siblings, but this is rarely the case (Bouchard, 1994).

Predisposition Is Not Determinism

"So you're telling me my political orientation is determined by my genes? Like I have no say in the matter?" Well, not exactly. What science is telling us is that we are likely born predisposed toward one political outlook over the other. We can conceptualize the interacting roles of nature versus nurture by imagining a knob that goes from zero to ten. In the case of political orientations, let's assume a setting of zero is extremely liberal and a setting of ten is extremely conservative. At birth, nature sets our knobs at a particular number (let's say two). Does this mean that an individual with this setting cannot grow up to become a staunch conservative? Of course not. What it does mean, however, is that this person will probably have to have more experiences that drive them toward conservatism in order to eventually become a political conservative than someone who has their knob set to eight, and thus is already predisposed to find that orientation intuitively appealing.

For those still holding their pitchforks, I'll make this very clear: nurture plays a critically important role. Through the forces exerted via environmental influence (social and otherwise), a person born with their knob at ten can become a proponent of liberalism. However, nature does play a role, as well, and that makes a lot of us uncomfortable.

When issues of genetic inheritance come up, we tend to get quite squirmy. But interestingly enough, we're usually only hesitant to acknowledge the role of nature in what are commonly perceived to be "non-physical" traits (though make no mistake, the brain is just as much a "physical" feature as an arm or a leg). For instance, if I were to show you two sets of parents — one where both partners are over seven-feet tall, one where both are under five-feet tall — would you predict that one pair would have a higher likelihood of having a tall child? I'm confident you would, and by doing so you're implicitly acknowledging the role of nature. Now this isn't to say that the short pair couldn't produce a child taller than the tall pair, but the probability of doing so is just not as great. The role of nature in these circumstances is typically seen as unquestionable, and admitting that genetics will have an influence in these outcomes is considered relatively benign. However, if I were to ask you whether two ultra-conservative parents would be more likely to have a child predisposed towards conservatism at birth (and not just through teaching), many of us would balk.

The Blank Slate And Its Unintended Consequences

Part of our reticence to acknowledge genetic inheritance is that we consistently make the mistake of equating probability with certainty. In other words, we have a tendency to reflexively condemn anything above a 0% probability as 100% determinism. But genetics are only probabilistic, and they only contribute a portion of what ultimately shapes our overall dispositions. An interesting anecdote to drive this point home comes from a Nobel prize winner who was approached by a sperm bank that only accepted sperm from "exceptional" applicants. When asked if he'd be willing to donate a sample, the man responded with something to the effect of "If you're looking for sperm that produces Nobel Prize winners, go solicit from my father" (who was, by all accounts, a just a "regular" guy).

This hesitance to acknowledge the role genes play in shaping how our brains work is an understandable one. For those attempting to suppress or deny the role of genetic inheritance in personality dimensions, I'd argue that you're wrong, but maybe for the right reasons. The notion that we are all "blank slates" is a comforting one for many, because if we all start as a blank slate then we all have an equal chance at success in life (or so the hypothesis goes). However, as noted by Steven Pinker in his well-argued book The Blank Slate: The Modern Denial of Human Nature, this hypothesis comes with many unintended consequences. He writes:

"If people are assumed to start out identical but some end up wealthier than others, observers may conclude that the wealthier ones must be more rapacious. And as the diagnosis slides from talent to sin, the remedy can shift from redistribution to vengeance. Many atrocities of the twentieth century were committed in the name of egalitarianism, targeting people whose success was taken as evidence of their criminality."

To frame it differently, this blank slate doctrine — though well-intentioned — can also serve to justify someone's place hanging from the bottom rungs of the socioeconomic ladder. "We all started off the same, right? So my position in society is simply a product of my effort and yours is simply a reflection of your lack of ambition." The blank slate hypothesis can serve to deny or dilute notions of social, economic, and racial privilege, and that's something I refuse to endorse.

Many people also fear that if people are inherently different from birth, it's a slippery slope before we start assigning a hierarchy of value to those differences which will inevitably lead to eugenic policies. This is a good fear to have, and we must always be vigilant of individuals who attempt to distort science to achieve these nefarious ends, but we need to stop immediately jumping to the conclusion that inherent differences subvert notions of equality. Equality is not a state only attainable through the rigid uniformity of a population. The foundation of equality does not crumble because we are not all exactly the same; the concept of equality is necessary precisely because we are not all exactly the same. Equality is not about what is, but about what ought to be. Pinker again captures this sentiment beautifully:

"The problem is not with the possibility that people might differ from one another, which is a factual question that could turn out one way or the other. The problem is with the line of reasoning that says that if people do turn out to be different, then discrimination, oppression, or genocide would be OK after all. Fundamental values (such as equality and human rights) should not be held hostage to some factual conjecture about blank slates that might be refuted tomorrow."

What This Means For How We Talk To Each Other

I was nervous writing this article. Not because I question the empirical validity of the facts I've presented, but because of how it might be received. It was just a few decades ago that the renowned scientist E.O. Wilson was unfairly chastised by the public, crucified by the media, and blacklisted by the scientific community simply for suggesting ideas similar to what have been presented here. The mere insinuation that we're not blank slates was taken as an implicit endorsement of racism, sexism, and eugenic policies.

But it's not.

It bears repeating: we're not blank slates, and that's okay. I happen to vehemently disagree with one political candidate in this coming election. Were I to believe in the blank slate doctrine, it becomes easy to see friends who endorse this particular candidate as unintelligent, selfish, and exclusionary. "If we all start with the same exact brains, and they're not on my side, they must be dumb, right?" But that's not necessarily the case. People are born with different political dispositions — along with differences across many other personality dimensions (Jang, Livesley, & Vemon, 1996) — in the same way some people are born predisposed to like chocolate ice cream over vanilla ice cream. This isn't to say that we need to simply accept people as they are when it comes to polarizing political topics and divisive matters of right and wrong. No, to the contrary, we should continue to fight for what we believe in, and continue to try to persuade others to see it our way. However, I hope we can try to do so with the civility engendered by this new perspective, recognizing that we don't always choose our preferences, sometimes they're just there.