I think that's a really interesting point, somewhat orthogonal to language mastery itself, and probably particularly impactful in Japan. A kid might grow up wi

I think that's a really interesting point, somewhat orthogonal to language mastery itself, and probably particularly impactful in Japan. A kid might grow up with perfect Japanese and be able to say anything, but choosing what to say can be another matter; how to make or respond to a request, how to deal with an affront, how to present yourself in a hiring interview, or a first meeting with a girlfriend's father... I'm a white Californian guy, and my wife's Japanese. Our kids are dual-nationality and growing up bilingual, but this was a major factor in the decision to raise them primarily in Japan for the first part of their lives — so they get those things intuitively. I myself went to university in Japan, and what I saw there convinced me this was a big deal. I was put into the "special Japanese" class, due to my wildly asymmetrical Japanese ability — I could speak Japanese an order of magnitude more effectively than I could understand it being spoken to me (reading/writing was still out of the question, as I'd only been learning for a year). But the interesting thing about that class was that all of my classmates were Japanese, who had grown up abroad for some/many years during childhood. So I got to witness their struggles with the finer points of the language and writing kanji (which was normal, and what you'd expect) and also with the implicit rules and norms of Japanese culture and interpersonal interaction. That latter bit was kind of mindblowing to me at the time. Since I was this white kid, nobody ever expected me to speak Japanese, or even be able to use chopsticks. (That's still largely true, incidentally, and it really seems to chafe at some long-term expats here, sometimes causing them to write epic rants about Japan...) In fact, I'd grown to understand, if I were to flawlessly execute the finer points of Japanese etiquette, it would veer into uncanny valley territory and make people uncomfortable — something like a chimpanzee putting on his own bowtie and sitting down to eat a formal meal with a knife and fork. But through that one class, I got to peek and to see how much different it was if you were Japanese. They had to be very careful when speaking their minds, to avoid sounding insolent, rude, or unqualified. Where I might get a reaction amounting to "oh, interesting to hear the American opinion", my Japanese buddies expressing the same thing might get "oh, you aren't really Japanese," or even essentially "fuck you, weirdo". It was interesting for me to see their struggle, and to realize it had nothing much to do with language. Being largely exempted from it, though, it wasn't that interesting to me... until I had kids. But hopefully they will be "bi-cultural" or whatever we call it, in addition to bilingual. (I am pretty confident that it will take a lot fewer years of practice for them to acquire "full Californian" status than it will to be perceived as "full Japanese".)