Well, my parents decided to migrate—I think Dad was afraid the Russians would invade W Europe and he would be hauled off again on forced labor. Nine year old me had no say in this, of course. So I turned 18 and naturalised, my parents did so a bit later.
I can speak Dutch—but the limited vocabulary of a 9-10yo. Mum and Dad decided to speak English at home to help me and my two sisters.