Why does Rannie Toomer turn her back on her own culture?

Rannie doesn't believe in "that swamp magic" that Sarah practices. She remembers all of the home remedies that she had taken as a child had come close to killing her. She also wants a white doctor, for she knows he has medicine and shots that he uses on white people that can make her baby better and strong. Rannie has sent for a white doctor by way of her white mailman hours earlier and has been waiting ever since. Rannie believes that a white doctor would not ignore her pleas to help a dying black baby.