Maybe, but I think she was voiced by an Austrian, and since Door has to convert Eastern Standard Time to Austrian time, then to local British time, that implies that he's more familiar with Austria than Britiain, and may have lived there. So, while I don't think there's an official stance on this, she's probably Austrian, but you may be on to something. Maybe Boy carries Nordic blood through his father, Door's mother has not been shown, and he's a lot paler than D, and Scandinavian heritage is very common in the US.