Whether you prefer Rush Limbaugh or Keith Olbermann has to do with your genes and your psychology, according to a new study.

People who are more conscientious and prefer order, structure and closure in their lives tend to be more conservative, whereas creative people who are open to new experiences tend to be more politically liberal, says John Jost, a psychologist at New York University who conducted an overview of previous studies involving a total of more than 22,000 participants from 12 countries.

But that psychological profile only pulls half the weight when it comes to determining people's politics, his review showed.

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The other half is genetic, as is revealed in studies of twins and their political bent, Jost says.

Politics in America

A number of sociologists have argued that political ideology died in America after World War II, because both the left and the right wings were heavily discredited at the time.

Jost says the latest research shows the opposite— that politics in America today are very much alive.

His previous research has suggested, for example, that more than 90 percent of college students can identify where their political beliefs fit on a scale running from the "left" (liberal) to the "right" (conservative), and that their affiliations strongly influence how they vote in elections.

Americans also appear to enjoy being involved in politics.

For instance, 44 percent of respondents to the 2004 National Election Study reported that they regularly listen to political talk radio.

Recipe for beliefs

Given our current political appetite, Jost next wanted to know whether liberals have different psychological traits than conservatives.

His "meta-analysis" of previous studies, including his own, showed that liberals seem to be drawn to chaos and novelty — for instance, they tend to support social change — whereas conservatives prefer reassurance and structure, and thus like to maintain the status quo.

Jost's findings, detailed in American Psychologist, suggest that environmental factors, or the types of situations people encounter in their lives, determine approximately half of their political preferences.

For example, when people fear death or terrorism, or are in a state of uncertainty, they tend to become more conservative, he said.

A study of World Trade Center survivors after 9/11 reported that 38 percent grew more conservative in the 18 months following the attacks, as compared with only 13 percent who became more liberal.

The other factor that determines a person's political beliefs is biology.

Research by John Hibbing, a University of Nebraska political scientist, showed that identical twins share more political beliefs than fraternal twins. They also, of course, share more genes.

"Forty, perhaps 50 percent of our political beliefs seem to have a basis in genetics," said Hibbing, whose studies were included in Jost's analysis.

While genetics are unlikely to "hardwire" people into being liberal or conservative, Hibbing said that genes could make people more or less likely to have certain values or react to situations in a particular way.

This knowledge could pave the way to a more tolerant society, Hibbing said.

"If you think your opponents are not just being willfully bullheaded, but rather have a kind of biological predisposition toward a set of beliefs, you might not spend as much time beating your head against the wall trying to get them to change," he said.

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