A woman your father impregnated who happens to be both your aunt and mother. The looped branch of the family tree.
One session changes family structure and status. Too many new titles starting with two people, aunt mother and uncle father.
Nine months before you were born, your aunt mother and uncle father hooked up at a family reunion. things happened - you got a mother, uncles, father, aunts,great aunts, great uncles, grand Oh fuck! it gets confusing but you get the point.