I think it's both. I think race plays part in it because the trend follows with the descendants who often absorb (parts) of the culture. There's also not that much in their culture that would explain it, to me. In my experience they are often hard workers. It's very taboo to say, but there is difference between races.
Is it racist to say that there's difference between races?
DEI is important, specially Diversity. In order to have diversity, you need to have different cultures. Mass immigration erodes diversity. Diversity exists by having different nations with different cultures, not one culture everywhere.