My parents were first gen immigrants. After recieving some terrible advice that they must not teach me their home language as a baby child because english will set me up for life (which it has, but still) they decided that they'd raise me completely english speaking. I don't actually know how they did it since my mother was new to the language and even though my father went to an english medium school over there... he has a strange way of english haha.
Also, they have the whooolleee rags to riches story going on, so "family" over there is kinda evil. Long story short they nearly convinced him to move back there to take care of his mother - when his sister literally lives across the city from her. Oh well, this meant that they began teaching me the letters for their language to prep going back home at likeeee 5ish. I had a perfect accent of both laguages, and would laugh whenever my father said something in a fun way hahaha.
But thankfully we didn't move back, I got a real citizenship instead and the language kinda just got left to the dust. Except for the fact that our parents (I gained a sibling) would speak thier language tons when they aren't talking to us. It is kind of odd, I think, but I don't really know any other way.
By the way, I hated english in school, hated language learning, and was all maths and science obsessed so its not my forte.
At night, my parents would speak downstairs and as I got older, obviously I wanted to know if they were talking about me. So in bed I'd start listening reaaalll hard for my home-name. By the way, its super funny but with an english accent - saying my homename means spiderwebs instead of sparks of light which is super funny - also the reason its my home-name hahaha.
And then with no effort at all - while I was simultaneously learning chinese (in school, I chose it over french because it was easier trust me) and sign language - I started picking up the language strangely really fast. Because I could guess what they were talking about from general context.
I got the music of the language - as in if I wanted to say something, I'd know the beat and I could hum the words but not actually say them. I could also somehow distinguish fancy version and colloquial quite soon in. I assume this is because technically I've heard it all my life but I usually completely tune it out in the day. Anyway, obviously my knowledge was extremely gappy and it wasn't entirely like I associated words to english meanings. It was... is weird.
Fast forward 2ish years, I could piece larger words together quite well simply from feeling the language - though pattern recognition is a big strength of mine. Then another few months, we were in the home country visiting the piranhas family there and obviously they know I can't understand a word they say. Also my parents don't really understand, I can't really explain how I interpret whole conversations, intricate jokes etc no longer with context but often can't give the english definition of a word when asked. And!! I was staring at them as if I understood what they were talking about with eachother (they don't speak english, my and my brother literally sit on opposite sides of the room with whoever and sign to eachother from sheer boredom usually). And I did mostly understand! It was hard, because I'm only used to my parents flavour of the language but thats why I was staring so intensely and they were like uhhhh she comprehend??
My parents said kinda.
Anywayyyy, we were in the store today, and they had whole complex conversation and I can proudly say I could translate it into english!! And reply back too :DD. I no longer have such a great accent but thats mostly because I overthink it. I also know like half the letters. Except for some reason they join letters and create new ones too so theres way way way more to learn. If I want to. But I'm reaaaaaaaaaaallly happy about that. Yay. Thats all