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The debate has been heavy in academic journals, where Mr. Fowler and a colleague are in a back-and-forth with Evan Charney at Duke University and William English at Harvard University, who argue that when other factors are controlled for, both of the genes Mr. Fowler identified as playing a role can be explained away.

In a follow-up study, Mr. Fowler confirmed his results for one of the genes he tested but found critics were right about the other one.

Mr. Fowler said there’s particular resistance among older researchers, who discount the influence of genes, but younger ones are more willing to accept it.

He theorized that the older generation was brought up during the civil rights era of the 1950s and 1960s, when genetics was used as an argument against black rights. Younger researchers, though, see a different civil rights movement, he said — that of gay rights — in which the genetic roots of homosexuality are used to argue for broader rights.

Researchers in both the United States and Britain have found biological differences between liberal and conservative brains that could support conclusions those in genopolitics are reaching.

It’s not so much that Republicans and Democrats always behave differently, but they are using different parts of their brains when they grapple with what could be seen as political questions.

The British researchers said conservatives tended to have larger amygdala, which are associated with processing fear. Liberals, meanwhile, showed more activity in the anterior cingulate cortex, which the researchers said could be linked to tolerance and ability to handle conflict.

Some in the practicing rooms say the more they look at the research, the more likely it appears that something is going on between biology and politics.

“Prior to 2003 everybody thought of this as being more of a societal phenomenon — messages you internalized growing up,” said Michael Oberschneider, a psychologist who runs Ashburn Psychological Services. “Since 2003, we’re looking more at the neurology of it all. What these researchers have found is real. They have found a strong correlation or relationship between certain areas of the brain and how we think about things consciously.”

Looking at his own practice, Mr. Oberschneider said he gets a sense that intensity is higher in this election, based on how much his patients are talking about it.

“The reason Obama and Romney are so present in my therapy room over the last year — this topic has come up so much — is because people also talk about what they’re passionate about. And there is a lot of passion about Romney and Obama,” he said.

Mr. Oberschneider said that was true even among children.

“I had a seven-year-old in the other day talking about Romney. And it was really endearing. The seven-year-old, with great passion, was talking about how Obama just should not be re-elected,” he said.