They claim it's because the different parties actually have physically different brains.
Using data from MRI scans, they found that people who identify themselves as liberal have a larger portion of the brain that handles complex matters. People who identify themselves as conservative have a larger portion of the brain that handles fear and anxiety.
Sorry, but your data pool is not scientifically sound.
You cannot explain brain-based behavior on politicians because they do not have one.
What? You want to show me EKG's you did on politicians? Stop it! My sides are aching!