James Fowler and Laura Baker have conducted a series of studies on voting behavior in families. They found that the party affiliation of adopted children tended to be similar to that of their adopted parents and siblings, suggesting that party affiliation was culturally transmitted. When the authors compared the voting behavior of a large sample of identical and fraternal twins, they found that identical twins were more similar than fraternal twins in regard to whether or not they voted, but no more similar in their choice of candidate. In sum, this work suggests that voter turnout is related to genetics, while party affiliation is related to environment.