 Fowler used twin studies of voter turnout in Los Angeles and the National Longitudinal Study of Adolescent Health to establish that the decision to vote in the United States has very strong heritability.He has also identified three genes that are associated with voter turnout and partisan attachment, specifically those regulating the serotonin and dopamine systems in the brain via the production of monoamine oxidase, 5HTT, and DRD2.More recently, he has shown evidence that social networks have a partly genetic basis.