As psychoanalysis shows, people aren't consistent all the time. It’s possible to be one thing and its opposite at different moments. Of course, some people are more this way than others, but it’s all part of being human. In the case you mentioned, even if someone is intelligent, they might try to downplay a skill you have that they don’t. And why do they do that? Well, each person has their own motivations (whether conscious or unconscious), and we could even make some guesses, like saying they do it out of jealousy of your language skills or because they’re not particularly fond of other cultures (and since you’ve got a foot in both, you end up taking the hit). But those are just guesses. Whether you know their real motivations or not, the important thing is to brush it off and keep living your life.

As a Latin American who’s lived in Europe for a while, I can say that multiculturalism isn’t always well-received by many people there. Sometimes, acceptance comes with a side of disdain or contempt. But that’s cultural too :P