Language acquisition and having an accent

I was talking to another one of my Taiwan-American friends today. Another one who came here when she was about 11-12 years old. So, that makes four people I know, including the other author on this blog (Yen Ching) who moved to the U.S. around 12-13 years old from Taiwan, who continue to live outside Taiwan (U.S. and Canada). I thought it would be kind of interesting to compare and contrast what each of these people is doing now, and some other minor facts about their lives I find interesting.

Three are female, one is male.

Female #1: moved to Rockville, Maryland (DC area) from Gaoxiong, Taiwan to live with Aunt and Uncle when she was 12 years old, placed directly in an American middle school with an ESL program geared towards native Spanish speakers. (They set her up with a Korean American girl to help her adjust in school? I couldn't believe that when she told me! Well, yes, I could -- the U.S. can be stupid like that.) Anyways, I met her when she was my roommate on the Virginia Tech study abroad to Tokyo, Hong Kong, and Guangzhou. She got a business degree and works in HR in the DC area, her partner is an American guy who does computer video game stuff, she became an American citizen at least 5 years ago and renounced her Taiwan citizenship. When she talks to me, she often calls the DC area "home" and Gaoxiong, Taiwan "home." She is entirely fluent in English, but she still has a slight accent, and most notably she, like me in French, has some slight grammar mistakes she always makes (even though she is otherwise flawless).

Female #2: my colleague in the UCSC Chinese history program. She moved to the U.S. right before middle school (?) but I think she also lived with her family. She also had a rough adjustment in a school without other native Chinese speakers and where she received very little help. She went on to Berkeley and then U of Chicago, and she married an American guy who does computer stuff (weird coincidence with #1? ;-) ). I think she's also a citizen, but I've never officially asked. She just spent 6 months in Japan learning Japanese. I think that, like me, she's never lived anywhere for more than a few years at a time. She admitted today she knows she still has a bit of an accent, even though her English is also flawless.

Female #3: my part-time language instructor on campus who is also from Taiwan and helps me with my translations. I know the least about her, but she has several things in common with #1 and 2: moved to the U.S. right before high school (age 13?), still has a slight accent even though her English is otherwise flawless and she understands all idioms/expressions, lived with family (although probably more native Chinese speakers around her), etc. (Also, all of these people have at one point or another tutored people's kids or other students in Chinese.)

Anyways... so you may have noticed one trend I'm getting at here: they all still have accents. I'm sure there is a linguist out there who could offer some theories about this, but I'm then curious as to why the last person, the one who writes on this blog (Yen Ching, who I shall call "E" :-) ), has virtually no accent? They all speak English flawlessly (no surprise given higher levels of education) but E has no accent. What I mean is that, with the other three people, you could quite easily conclude they moved here before adulthood or as teenagers, but with E you might mistake him for being a second generation Taiwanese or Chinese-American rather than someone who happened to move to the U.S. and learn English nearly from scratch (like the others did). So what were the differences? Was it that he didn't live with family but instead other American students? Was it the location in a fairly remote area of the U.S. that did it? Was it necessary in his case to speak more clearly than others because this more remote area was unfamiliar with non-native English speakers and therefore would not have otherwise understood him?

And finally, does age really have an impact on accent? I've been told that my accent in French almost makes me sound like a native speaker, and I've been mistake for one, until I screw up something grammatically. (Then I'm usually mistaken for a Swiss or Canadian.)