A choice quote from the abstract: Here, we hypothesize that individuals with a
genetic predisposition toward seeking out new experiences will tend to be more
liberal, but only if they are embedded in a social context that provides them
with multiple points of view.
Note that they didn't discover a gene at all. They did show that, among people with a genetic variant already known to predispose people toward novelty seeking, having more friends is positively correlated with self-reported liberal ideology (and among people without the variant, there is no correlation between ideology and number of friends).