As some commentators noted, they don’t always go together. Anyway, multiculturalism in it’s extreme form doesn’t work. I mean, some countrified Blacks could get along with Whites well, but inner-city types couldn’t.
Regarding other foreign cultures, some like the Muslims have a tough time with integration, especially if it’s a radical one.
Now, with gays/trannies, they definitely exhibit a “foreign culture” and it’s not healthy and compatible with the West.