My grandfather was born on the reservation in Ada, Oklahoma, as was his mother, grand-father, and great-grandfather. Does this mean that they were Chickasaw? My grandfather once told me that his great-grandmother was Creek, and another relative said they were Cherokee, and my great-grandmother was a teacher on the reservation. So I guess I'm asking if members of other tribes could have also be born and lived there, or would that be unlikely, and therefore they were most likely Chickasaw (or part Chickasaw)?