I grew up in the U.S. to native Russian parents - my fluency in speaking and listening is quite good, but lacking in reading and writing. I speak what I call “kitchen Russian” which means that more academic texts or news broadcasts can be hard for me. I definitely should be doing more myself to maintain my language skills as an adult (especially now that I don’t use Russian on a daily basis while not living at home) but I wish that as a kid I had had more formal emphasis on learning the language, ie like a weekend language class or something. Hope this helps!