I haven't read the paper yet, but it's not that surprising. I think it's about sociology more than biology. In the US, African Americans vote overwhelmingly fo

I haven't read the paper yet, but it's not that surprising. I think it's about sociology more than biology. In the US, African Americans vote overwhelmingly for democrats for example. Skin color therefore becomes a very good predictor of political orientation. You can probably extend this to states being populated from various migration waves, say 'people who look like Danes vote for republicans because state X was populated by Danes and votes Republican' . Carry this across generations/education, and you may have an explanation.