Children differ, as any parent of two or more knows. Some babies sleep through the night, others are always awake; some are calm, others are fussy; some walk at an early age, others after a long wait. Scientists have proved that genes are responsible for these early differences. But people assume that as children get older and spend more time under their parents’ influence, the effect of genes declines. They are wrong.
For a century or more, we have understood that intelligence is largely inherited, though even today some mistakenly rail against the idea and say that nurture, not nature, is all. Now we know that much of our personality, too, is inherited and that many social attitudes have some degree of genetic basis, including our involvement in crime and some psychiatric illnesses. Some things do result entirely from environmental influences, such as whether you follow the Red Sox or the Yankees (though I suspect that Yankee fans have a genetic defect). But beyond routine tastes, almost everything has some genetic basis. And that includes politics.
When scholars say that a trait is “inherited,” they don’t mean that they can tell what role nature and nurture have played in any given individual. Rather, they mean that in a population—say, a group of adults or children—genes explain a lot of the differences among individuals.
There are two common ways of reaching this conclusion. One is to compare adopted children’s traits with those of their biological parents, on the one hand, and with those of their adoptive parents, on the other. If a closer correlation exists with the biological parents’ traits, then we say that the trait is to that degree inherited.
The other method is to compare identical twins’ similarity, with respect to some trait, with the similarity of fraternal twins, or even of two ordinary siblings. Identical twins are genetic duplicates, while fraternal twins share only about half their genes and are no more genetically alike than ordinary siblings are. If identical twins are more alike than fraternal twins, therefore, we conclude that the trait under consideration is to some degree inherited.
Three political science professors—John Alford, Carolyn Funk, and John Hibbing—have studied political attitudes among a large number of twins in America and Australia. They measured the attitudes with something called the Wilson-Patterson Scale (I am not the Wilson after whom it was named), which asks whether a respondent agrees or disagrees with 28 words or phrases, such as “death penalty,” “school prayer,” “pacifism,” or “gay rights.” They then compared the similarity of the responses among identical twins with the similarity among fraternal twins. They found that, for all 28 taken together, the identical twins did indeed agree with each other more often than the fraternal ones did—and that genes accounted for about 40 percent of the difference between the two groups. On the other hand, the answers these people gave to the words “Democrat” or “Republican” had a very weak genetic basis. In politics, genes help us understand fundamental attitudes—that is, whether we are liberal or conservative—but do not explain what party we choose to join.
Genes also influence how frequently we vote. Voting has always puzzled scholars: How is it rational to wait in line on a cold November afternoon when there is almost no chance that your ballot will make any difference? Apparently, people who vote often feel a strong sense of civic duty or like to express themselves. But who are these people? James Fowler, Laura Baker, and Christopher Dawes studied political participation in Los Angeles by comparing voting among identical and fraternal twins. Their conclusion: among registered voters, genetic factors explain about 60 percent of the difference between those who vote and those who do not.
A few scholars, determined to hang on to the belief that environment explains everything, argue that such similarities occur because the parents of identical twins—as opposed to the parents of fraternal twins—encourage them to be as alike as possible as they grow up. This is doubtful. First, we know that many parents make bad guesses about their children’s genetic connection—thinking that fraternal twins are actually identical ones, or vice versa. When we take twins’ accurate genetic relationships into account, we find that identical twins whom parents wrongly thought to be fraternal are very similar, while fraternal twins wrongly thought to be identical are no more alike than ordinary siblings.
Moreover, studying identical twins reared apart by different families, even in different countries, effectively shows that their similar traits cannot be the result of similar upbringing. The University of Minnesota’s Thomas Bouchard has done research on many identical twins reared apart (some in different countries) and has found that though they never knew each other or their parents, they proved remarkably alike, especially in personality—whether they were extroverted, agreeable, neurotic, or conscientious, for example.
Some critics complain that the fact that identical twins live together with their birth parents, at least for a time, ruins Bouchard’s findings: during this early period, they say, parenting must influence the children’s attitudes. But the average age at which the identical twins in Bouchard’s study became separated from their parents was five months. It is hard to imagine parents teaching five-month-old babies much about politics or religion.
The gene-driven ideological split that Alford and his colleagues found may, in fact, be an underestimate, because men and women tend to marry people with whom they agree on big issues—assortative mating, as social scientists call it. Assortative mating means that the children of parents who agree on issues will be more likely to share whatever genes influence those beliefs. Thus, even children who are not identical twins will have a larger genetic basis for their views than if their parents married someone with whom they disagreed. Since we measure heritability by subtracting the similarity among fraternal twins from the similarity among identical ones, this difference may neglect genetic influences that already exist on fraternal twins. And if it does, it means that we are underestimating genetic influences on attitudes.
When we step back and look at American politics generally, genes may help us understand why, for countless decades, about 40 percent of all voters have supported conservative causes, about 40 percent have backed liberal ones, and the 20 percent in the middle have decided the elections. On a few occasions, the winning presidential candidate has won about 60 percent of the vote. But these days we call a 55 percent victory a “landslide.” It is hard to imagine a purely environmental force that would rule out a presidential election in which one candidate got 80 percent of the vote and his rival only 20 percent. Something deeper must be going on.
All of this leaves open the question: Which genes help create which political attitudes? Right now, we don’t know. To discover the links will require lengthy studies of the DNA of people with different political views. Scientists are having a hard time locating the specific genes that cause diseases; it will probably be much harder to find the complex array of genes that affects politics.
There are problems with the observed link between genes and politics. One is that it is fairly crude so far. Liberals and conservatives come in many varieties: one can be an economic liberal and a social conservative, say, favoring a large state but opposing abortion; or an economic conservative and a social liberal, favoring the free market but supporting abortion and gay rights. If we add attitudes about foreign policy to the mix, the combinations double. Most tests used in genetic studies of political views do not allow us to make these important distinctions. As a result, though we know that genes affect ideology, that knowledge is clumsy. In time, I suspect, we will learn more about these subtleties.
Further, it’s important to emphasize that biology is not destiny. Genetic influences rarely operate independently of environmental factors. Take the case of serotonin. People who have little of this neurotransmitter are at risk for some psychological problems, but for many of them, no such problems occur unless they experience some personal crisis. Then the combined effect of genetic influences and disruptive experiences will trigger a deep state of depression, something that does not happen to people who either do not lack serotonin or who do lack it but encounter no crisis. Recently, in the first study to find the exact genes that affect political participation, Fowler and Dawes found two genes that help explain voting behavior. One of the genes, influencing serotonin levels, boosts turnout by 10 percent—if the person also attends church frequently. Nature and nurture interact.
The same is probably true of political ideology. When campus protests and attacks on university administrators began in the late 1960s, it was not because a biological upheaval had increased the number of radicals; it was because such people encountered events (the war in Vietnam, the struggle over civil rights) and group pressures that induced them to take strong actions. By the same token, lynchings in the South did not become common because there were suddenly more ultra-racists around. Rather, mob scenes, media frenzies, and the shock of criminal events motivated people already skeptical of civil rights to do terrible things.
Another challenge is politicized assessment of the genetic evidence. Ever since 1950, when Theodor Adorno and his colleagues published The Authoritarian Personality, scholars have studied right-wing authoritarianism but neglected its counterpart on the left. In his study of identical twins reared apart, Bouchard concludes that right-wing authoritarianism is, to a large degree, inherited—but he says nothing about the Left. This omission is puzzling, since as Bouchard was studying twins at the University of Minnesota, he was regularly attacked by left-wing students outraged by the idea that any traits might be inherited. A few students even threatened to kill him. When I pointed this out to him, he suggested, in good humor, that I was a troublemaker.
Yet if you ask who in this country has prevented people from speaking on college campuses, it is overwhelmingly leftists. If you ask who storms the streets and shatters the windows of Starbucks coffee shops to protest the World Trade Organization, it is overwhelmingly leftists. If you ask who produces campus codes that infringe on free speech, it is overwhelmingly leftists. If you ask who invaded the classroom of my late colleague Richard Herrnstein and tried to prevent him from teaching, it was overwhelmingly leftists.
A better way to determine if authoritarianism is genetic would be to ask people what the country’s biggest problems are. Liberals might say the inequality of income or the danger of global warming; conservatives might indicate the tolerance of abortion or the abundance of pornography. You would then ask each group what they thought should be done to solve these problems. An authoritarian liberal might say that we should tax high incomes out of existence and close down factories that emit greenhouse gases. A conservative authoritarian might suggest that we put abortion doctors in jail and censor books and television programs. This approach would give us a true measure of authoritarianism, left and right, and we would know how many of each kind existed and something about their backgrounds. Then, if they had twins, we would be able to estimate the heritability of authoritarianism. Doing all this is a hard job, which may explain why no scholars have done it.
Genes shape, to varying degrees, almost every aspect of human behavior. The struggle by some activists to deny or downplay that fact is worrisome. The anti-gene claim is ultimately an ill-starred effort to preserve the myth that, since the environment can explain everything, political causes that attempt to alter the environment can bring about whatever their leaders desire.
The truth is that though biology is not destiny, neither is it an easily changed path to utopia.