Taboos have existed across the world for eons, though what is considered taboo is constantly in flux over time.  The word itself stems from the Tongan word tabu or tapu, meaning "forbidden". These particular subjects or actions invoke a widespread sense of disgust, shock,  repulsion, or a belief that only a certain or group may participate in said action. How does a taboo come to be? What variables (religious, health/safety, social, cultural, food-related, etc...) influence them? Is having certain taboos a good thing? Or does the inhibited communication or unease around certain subjects prevent learning and growth of a society? Somewhere in between? I suggest researching different taboos throughout history and different societies, what you find may be interesting!