But if you believe in Panspermia, the process where the more people breed the more room they need, you understand as they spread they took their traditions with them. Worldwide. But unscrupled people always pop up and twist these traditions into some perversion for their own nefarious purposes. Kinda sorta like when I was a little kid and we had Christmas. But now we have The Holiday Season. ;-)
quibble, panspermia refers to the seeding of life (or its components) from space; the word you’re looking for is probably diffusion.