Throughout history, taboos have been established to limit and control society, and help to retain a status quo. “Best not mention it” is the nodded instruction to put something off limits in the family living room. In the 20th century, in the UK, societal disapproval would be rained down on those who ate something other than fish on Fridays, or children who played outside on a Sunday, or an adult who didn’t wear a hat to church. And in the US today the Westboro Baptist Church tells its female followers that it is forbidden for them to cut their hair. But why? Who decided these were the rules, and how do they change?