Well, if being 1/8 of an ethnicity means that a great- grandparent was that ethnicity and 1/8= 12.5%, if she was 15%, she had American Indian blood from another great- grandparent.. There are those Indian nations who only need one to have a great- great grandparent who was a full- blooded tribal member to qualify for citizenship in that nation. My own great- grandmother was from a town in Southern Louisiana that is now part of the Chitimacha Reservation ( I know this because I visited the town, Charenton, LA, for my fortieth birthday and I visited their cultural museum. Their constitution is on display there and that includes a 1/16 blood quantum as a citizenship requirement. I visited the graves of that part of the family in the necropolis that surrounded the Catholic Church of the Immaculate Conception in that town. My great- great- great- great grandparents, Charles Pecot and Claire Sigur are buried there).