It's not taboo though is it. People go on and on about immigration and there are entire media outfits that are devoted to casting foreigners as threats while promoting the idea that 'these people are not as good natives, have lower IQ, are more violent and less productive', which is typically based on outright lies and prejudice. Beliefs about immigrants are entirely warped to cater to a smaller subset of the population which has a hard time dealing with change while they grip with tremendous entitlement to mythical constructions of the past.
> You only have to go back 2-3 generations for homogeneity to be the overwhelming norm
A very curious statement. Europe's history is one characterised by migration and constant changes in demographics. There have always been groups of people at odds with one another because they were different enough to be seen as a threat. Every generation has struggled accepting new groups of people with both good and bad results.