The problem is not the foreign people, it's the pressure from extreme anti-racists to make everything "racially diverse". These anti-racists the internet calls "Social Justice Warriors" (who ironically are racist themselves by perceiving race in everything) want needless side characters of diverse sexes and sexualities shoved into every story and artistic creation because doing the opposite would be "sexist" or "racist". These people don't realize that not being included doesn't mean that they were excluded. These people are the ones who are poisoning your culture by forcing it to collide with the cultures of foreingers when the foreingers don't really care either way. It's kind of like how people freak out over the word "nigger" when actual black people have said that they don't give a damn.
Then there's the whole talk about cultural enrichment. The activists who drive that line often expect the national people to be racist towards the foreign people (ironically being racist again), so they push the enrichment idea on the people forcefully which pisses them off instead of making them embrace it. In fallacy the people get pissed off towards the foreigners instead of the cultural anti-racists and the anti-racists have ended up causing more racism.
I'm from Finland and a year or so ago the government funded the filming of a movie in memory of our national hero Mannerheim. The movie was about African tribal warfare with Mannerheimin shoved somewhere in there. Instead of being a movie about the winter war, the memory of one of Finland's most recognized figures was subjected to this ridiculous pseudoartistic garbage. There was a backlash and people against the idea were called racists in a predictable move by the anti-racists.
The behavior, beliefs nor the IQ of a person is in no way a direct causation of their race, sex or gender.