STEVE INSKEEP, HOST:
This story starts with a quiz. Here's your quizmaster, Noel King.
NOEL KING, BYLINE: It comes from political scientist John Hibbing at the University of Nebraska. He's going to describe two towns, and you have to guess which one is liberal and which is conservative. Here's town number one.
JOHN HIBBING: The schools would stress, you know, patriotism and respect. And it would be a very rules-based educational system. The houses would be fairly similar. The lawns would be very nicely kept and beautifully green and mowed. The town would be quiet, with lots of churches.
KING: All right, and here is town number two.
HIBBING: The schools would be based more on experiential kinds of things rather than rote memory. People would prefer older houses with wooden floors rather than wall-to-wall carpeting. They would keep the yards natural, lots of bars and community theaters and foreign films - more of those than churches.
KING: This quiz was probably pretty easy for you. And to explain why, we're joined now by NPR's social science correspondent, Shankar Vedantam. Hi, Shankar.
SHANKAR VEDANTAM, BYLINE: Hi, Noel.
KING: So the first town, I'm guessing, was conservative. And the second one was liberal, right?
VEDANTAM: Exactly. Now, Hibbing is drawing on fairly traditional stereotypes about liberals and conservatives. Conservatives prefer order and rules. Liberals prefer experiential schools and community theaters. Now, those are stereotypes, which means that there are going to be liberals who hate community theaters and conservatives who despise churches.
But the question that Hibbing and others are asking is, how come these stereotypes are so often accurate? If being liberal and conservative is all about our political views, how come these labels describe all kinds of other things about us, from the kinds of food we prefer to eat to the kinds of poetry we love?
KING: To where we want to hang out. So he's arguing that our political views spring from something deeper than just our beliefs about big government or small government.
VEDANTAM: Precisely. He's arguing that our political preferences, at least in part, come from our psychological and biological predispositions. The most compelling evidence for this comes from studies involving large numbers of twins, some of whom are identical and some of whom are fraternal. Identical twins share the same genes. Fraternal twins share fewer genes. Identical twins turn out to have more political preferences in common than fraternal twins do, even though each twin pair presumably shared the same family and upbringing.
HIBBING: Height, for example, turns out to be about 80 percent heritable when you subject it to the same kind of design. Personality traits are about 56 percent, political views, 30 to 40 percent.
KING: Thirty to 40 percent, so he's saying some part of our political beliefs come from biology.
VEDANTAM: Yes. And of course that conclusion upset a lot of people.
HIBBING: And they tended to over-interpret those results and make it sound like we were saying that everything was genetic. But, you know, if it's 34 percent genetic, that obviously leaves, you know, 50, 60, 70 percent that comes from the environment. So all we're saying is that that genetic component is not zero. But apparently that was enough that some people were upset about that.
VEDANTAM: What Hibbing and his colleagues are saying is that biology and psychology play a role in our political preferences, Noel. Liberals and conservatives in the United States often accuse one another of stupidity or malice. But if Hibbing and his colleagues are right, one reason we might not see the world the same way is because we're simply not wired the same way.
KING: That is a nice way of looking at it.
VEDANTAM: Indeed, it offers some compassion for the other side.
KING: Shankar Vedantam is host of the Hidden Brain podcast, where you can learn more about how psychology shapes our political views. Thanks, Shankar.
VEDANTAM: Thank you, Noel.
(SOUNDBITE OF SHIGETO'S "A CHILD'S MIND") Transcript provided by NPR, Copyright NPR.