A recent study in London, led by Ryota Kanai, showed that political ideology is partially based on biological differences in the brain. Conservatives were found to have a larger amygdala and a smaller anterior cingulate cortex than their liberal counterparts. This study is fascinating and comes with some serious implications and explanations.
The amygdala, of course, is the brain's fear center and is linked to emotional learning. Since this area is larger in conservatives, it means that they will be more fearful in their reactions and feelings and rely more on emotion than liberals when making decisions and formulating opinions. Liberals on the other hand are more likely to be realistic and rely on facts when analyzing the issues, while being less adept at recognizing threats than conservatives. This overstimulation in the amygdala explains why President Bush may have invaded Iraq on the pretense that there were weapons of mass destruction hidden in the country. Although Saddam Hussein was a great threat, the enlarged amygdala in the brains of Bush and other conservatives may have made them have excess fear, leading them to risk human lives and waste billions of dollars to find WMDs that did not really exist.
The anterior cingulate cortex is a region of the brain that is involved in decision making. Since this area tends to be larger in liberals, they typically are better at managing conflicting information. This is somewhat linked to the conclusions in the previous paragraph, which leads me to conclude that the typical makeup of a liberal brain makes them more adept at making informed decisions and opinions. This may also explain some religious bias, typically from conservative-minded people. Many are presented with clear, unbiased, and peer-reviewed research on evolution, but are unable to accept the facts. A smaller anterior cingulate cortex could be a cause for why they cannot make sense of the mass of evidence for evolution, and instead fall back to simpler, but incorrect, explanations like creationism.
Of course, this are just trends measured in a study, and are not an "ultimate solution" as to who is correct. It is just a scientific study that gives us some general, correlative information and offers an explanation to why people think how they do.