To my ear my kids have English accents but they do sound different from their friends. The middle one has the strongest twang. The little one has the strongest/purest English accent which is probably down to Speech Therapy and spending alot less time in the states growing up. The oldest two spent almost every summer there until the were 9 and 10. The little one has only been three times-when she was 8 months, 21/2 and 3.
They do use alot of American words and phrases-and so does my husband.
Braids, math, candybar, barrette, bunch, grab, gotten, dumb, bathroom, ass, butt.