>>His parents never got the chance to go to college and do not speak English.
Clearly the kid didn’t get his work ethic from his parents. Four years in country and they don’t speak any English? Pathetic.
Nobody said they didn't speak any English. Spend 4 years in Vietnam and see how much Vietamese you know. I bet it won't be much.
I think you underestimate the difficulty an adult faces in learning a new language. My wife learned English as a teen before coming here as a nurse in the 1970’s and she got a Masters while working in a hospital nights. Yet she still has words she cannot properly pronounce. I’ve been studying Thai off an on for the 35 years we’ve been married and I have huge problems in speaking.
The base reasons are that adults have a hard time speaking in one language and often thinking in another while young people usually have an easier time beginning thinking in the new language. Second, unlike English, Asian languages are most often tonal where a low, mid, high or transitioning tone give a word totally different meanings. Finally, this boy’s parents are most likely working for Vietnamese speakers for long periods of time. You may have a language ability or intellect sufficient to quickly pick up a new language quickly but I guess I’m too stupid.