Curiosity: Psychotic condition could be transmitted.
When you live in close proximity to someone, it's common for illness to spread from one person to another. But mental illness? It's possible. The phenomenon is technically called shared psychotic disorder, but it's most famously known as folie à deux. The first case of the condition was documented in the 19th century, and described a 30-something married couple, Margaret and Michael. The couple shared a delusion that people were sneaking into their house at night spreading dust, dropping pieces of fluff, and wearing down the soles of the couple's shoes.