It’s Friday the 13th, and millions of people are on edge, fearing a calamity with personal or global repercussions-a broken leg, a stock market crash, or the trigger pulled for World War III.

Why all the anxiety? In short, because the fear is ingrained in Western culture, according to experts.

“If nobody bothered to teach us about these negative taboo superstitions like Friday the 13th, we might in fact all be better off,” said Stuart Vyse, a professor of psychology at Connecticut College in New London.