Not to mention when that 'English' that you learn from them is a mix of non-existing, made-up words in three languages and bad pronunciations.. and voilà, you can only use that 'language' with your parents.
That's what it's like with parents that know another language but didn't have formal education so you speak to anyone in that language but you're crude and using slang for everything
We did that. My spouse speaks native Korean, I speak Tagalog as a second language (English native), and our kids only know English. I think Tagalog is quite useless so I haven't bothered teaching them, but my spouse has no excuse. I speak a little German, but not enough to teach them, just enough to curse while driving.
I've resorted to learning Spanish with my kids, which is at least useful, but I'm sure I'm teaching the wrong.
You never know, they might find out you speak Tagalog and, wanting to have learned another language, wonder why you never bothered to teach them. What you consider to be useless might be very intriguing to them.
Eh, I've told them, but they don't seem to care. I teach them a few words here and there, but they seem much more interested in Spanish because our neighbors are hispanic.