Fowler matched up 396 twins from the registry and voting records. He separated monozygotic (identical; share 100% of genes) and dizygotic (fraternal; share 50% of genes) twins to determine the extent that genes have on voting. Only same-sex twins were used in order to limit variables. The voting records used included eight elections from 2000 to 2005.
The results of their findings found that 53% of the variance in voting behavior can be accounted for by genetic affects; in simpler terms, genes play a role in political participation. Shared environment accounted for 35% of the variance. It is widely assumed that MZ and DZ twins share comparable social environments. If this happens to be false, the genetic effect is much greater.
This study confirms outcomes of similar studies, but for different reasons. The voting behavior of parents has been known to have an effect on the political participation of their children. This was often assumed as a result of social influence, but this recent study shows that biological factors may play a great role since shared environment only played a small role in this study. Also, this study confirms that voter behavior is habitual. What was always assumed to be reduced from reinforcement learning may actually be due to genetic variation.
Although this study finds genes as a predictor for political participation, we still do not know which genes are responsible or why. This study will begin to help political psychologists understand biological reasons for voting and open up the minds of many others.