I was born in Russia and moved to the US at the adolescent and prepubescent age of 12. Before my relocation to the US I had never really been exposed to the English language at large, and after my relocation I was promptly forbidden to speak Russian at home and school for my parents, desperately, wanted me to nail down English fast.
And nail down English fast I did in a sense that I was able to read and write in it quite well after a couple of years of Remedial English, but I was, however, never able to ditch my thick foreign accent and neither have I been to able, up to the present day, to audially comprehend the English language very well.
For example, I cannot watch English movies without subtitles and I have difficulties watching TV, as well, though in all fairness, I have no trouble at all communicating with people I know well, howbeit I still have, sometimes, a hard time understanding strangers when they speak "rather" fast.
And so the second part of my question is: did my parents "screw" me up by forbidding me to use Russian and not speaking to me in the language both they and I knew the best, at that tender age, and instead exposing me to their, at times imperfect and always heavily accented, English thus leaving me semi-lingual or no matter what they did I would still never be able to get down English native-like, at that age?