THE EVIDENCE IS MOUNTING...

that political orientations are influenced by genes in addition to the environment.  Here's the citation:

Funk, C. L., Smith, K. B., Alford, J. R., Hibbing, M. V., Eaton, N. R., Krueger, R. F., Eaves, L. J. and Hibbing, J. R. (2013), "Genetic and Environmental Transmission of Political Orientations." Political Psychology, 34: 805–819. DOI: 10.1111/j.1467-9221.2012.00915.x