I am from the Boston area (without a Boston accent) and I rated 90% US. My teen daughter who is also from this area and to me sounds like she has an even "flatt

I am from the Boston area (without a Boston accent) and I rated 90% US. My teen daughter who is also from this area and to me sounds like she has an even "flatter" American accent rated 64% US, with the words "call" and "small" flagged as moderately British. My teen son (who sounds identical to her) was 95% U.S. I lived in London when I was younger and can imitate some local accents; my "upper crust" accent was rated about 65% U.S. on the first try and 86% British on the second. My "Norf London" was 50/50 on the first try, 65% U.S. on the second.