Comment by fluoridation

I mean, it's basically inevitable, isn't it? Cultural heterogeneity is born out of isolation. If two groups of people are in constant contact, they'll never ever stop speaking the same language and having the same traditions. Conversely, if two originally distinct cultures start to interact regularly (even more so if closely) they'll eventually merge into one. People are more willing to give up on traditions and cultural norms than to have constant friction with their neighbors.