I'm late-deafened so what I'm about to say was before I started losing my hearing.
I grew up in the South (GA). My parents were transplants from the Mid-Atlantic. When I was 11 we moved back to the Mid-Atlantic. As an adult people have, and still, ask me if I'm from New England or England. I've never been to either.
I guess it's from a combination of things. My "northern" parents, my southern friends, the fact that my sister who is closest in age to me had a small speech impediment and that I was still "impressionable" when I moved up here.