I’m a self-professed culture nerd. The feeling I get when I solve a cultural dilemma—like why the Italian tour operator said my colleague was taking advantage of him, or how to build trust with a French colleague—gives me a rush that makes me feel like the next Nelson Mandela. That’s because I’ve also seen the darker side of culture. People are quick to distrust each other around our great, big planet. We notice each other’s differences, and more often than not, we say, “No, thank you,” and retreat back ...