US voters head to the polls today in a midterm contest that most number-crunchers believe will result in Republicans taking control of at least one house of Congress. Messages have been calibrated in order to snare that mythical election-season beast: the “swing voter”. But no amount of campaigning might sway some members of the electorate, because it turns out that how voters pull the lever today is written, in part, in their DNA.

According to research conducted by University of California–San Diego behavioral scientist James Fowler, certain genetic factors can predispose some people to be more liberal, provided that they’re social butterflies as well. Fowler’s previous work has found that alcoholism is contagious among social networks, and that researchers can track the spread of infectious diseases by monitoring people’s Facebook friends. His most recent study of 2,000 adults, published in the Journal of Politics, found that people who possessed the 7R variant of the DRD4 gene and had a lot of friends in adolescence were more likely to self-identify as liberal. DRD4, which codes for a dopamine receptor, has also been linked to attention deficit disorder, impulsivity, gambling and heroin addiction. The train of reasoning goes something like this: people with DRD4-7R are more likely to seek out new experiences and new friends, thus exposing them to lots of different lifestyles and making them more likely to hold opinions and support policies that are friendly to the poor, dispossessed, ethnic minorities, etc.

This isn’t the first attempt to prove that political sensibilities are ingrained at birth. A 2006 longitudinal study of 100 nursery schoolers in Berkeley, California found that three-year-olds who possessed negative characteristics (according to their teachers) eventually grew up to be self-identified conservatives 20 years later. The study, understandably, irked a few conservative commentators. Studying Republicans in Berkeley is like surveying the henhouse to write an academic treatise on foxes.

And how scientifically valid are labels like “conservative” and “liberal”, anyway? As comedian Jon Stewart said this past weekend at his Rally to Restore Sanity: “Most Americans don’t live their lives solely as Democrats, Republicans. liberals or conservatives. Most Americans live their lives more as people that are just a little bit late for something they have to do.” Thankfully the polls are open late tonight, so get out and vote with your conscience — or your DNA.

Image by mollypop via Flickr Creative Commons