you know, that's an interesting point about accents and age. i was 10 when 11 came to this country. i knew english very well from being in india and spoke it fluently (in fact, i was placed in honors english right away much to everyone's surprise). my accent literally changed within a month. you'd never know that i was raised partly in india. people to this day make those comments, "oh your english is good, you have no accent".
i have this theory that you cannot change your accent after a certain age, and i think that it might be around 14 or 15. because i've met people who have a thick indian accent if they've come here after 16 or so. the one person who has foiled this theory is my cousin who came here at age 19 and has an american accent now.
interesting, indeed.