That's saying why we even assume someone called Goldmoon must be N.A.
In fairness, everything about Goldmoon's background and culture was N.A.-inspired and derived, and her appearance was unusual for her people. Then again, since the Plainsmen of Ansalon weren't isolated from the other cultures, the possibility of ancestral genetics from another ethnic group is highly plausible.
(Ansalon's diversity is interesting--for a continent smaller than Australia, it has white, black, and American Indianesque residents, with no indication of migration from elsewhere. And this has been part of the setting since 1984.)