This is actually a huge factor. There's a lot of research out there that shows people grow up smarter if they learn a second language starting very young. If they're fluent by their teenage years, they have significantly higher success in many areas of life. I forget if it affected IQ or not, I don't think I saw anything about that, which would make sense. Americans are barely taught this bastardized, watered down form of English. And with social media becoming so massive, an entire new lexicon is coming into being- words used to sort of remain trendy for a significant time period. Think about shit like "radical, tubular" and such from the '90s. Today, words like "lit" come and go like the damned wind. And the language is getting dumber and dumber, less complex. I think a lot of Americans have trouble expressing themselves, instead regurgitating shit they've heard from their favorite celebrities or other people they know, simply because they lack the words to capably express what they're trying to get across. It's a very inefficient form of the language.