Disgust reactions against gays are correlated with negative attitudes toward same-sex marriage. That isn’t to say that conservatives are less tolerant of or hardwired to dislike gays. “I think the best way of looking at this is conservatives are wired to be a little more easily disgusted and fearful,” Stewart says. “They are a little bit more wired to defensiveness in their environment.” But Stewart has also found that even liberal minds harbor implicit associations between disgust and the LGBT community.

In a recently published experiment, Stewart and his colleagues demonstrated that the presence of a disgusting odor decreased support of gay marriage. Random samples were sorted into either into an odor group (the researchers added a vomit-like smell to a room) or control groups (no odor). The participants were then asked about their feelings on an array of social and political issues. The results are clear: In the disgust condition “participants exposed to the smell … reported increased subjective disgust and more politically conservative attitudes concerning gay marriage, premarital sex, pornography, and Biblical truth.” The disgusting odor had no impact on opinions on nonsexual political matters, such as tax cuts or immigration.