Are political leanings all in the genes?

The race to become the most powerful politician on earth is well under way, and the US is gripped by election fever. In newsrooms and bars across the land, liberals and conservatives are slugging it out, trying to convince each other that their way of thinking is right. They may be wasting their breath.

According to an emerging idea, political positions are substantially determined by biology and can be stubbornly resistant to reason. "These views are deep-seated and built into our brains. Trying to persuade someone not to be liberal is like trying to persuade someone not to have brown eyes. We have to rethink persuasion," says John Alford, a political scientist at Rice University in Houston, Texas.

Evidence to support this idea is growing. For example, twin studies suggest that opinions on a long list of issues, from religion in schools to nuclear power and gay rights, have a substantial genetic component. The decision to vote rather than stay at home on election day may also be linked to genes. Neuroscientists have also got in on the act, showing...