grandmother was raised by her biological aunt. The aunt was married. Her younger sister came to stay for the summer. The little sister got pregnant by the older sisters husband. Gave birth to the baby, but the older sister and her husband raised the child as their own. My Grandma found out when she was a teenager and the "aunt" came to visit. Grandma walked in after school and her "mom" and "aunt" were sitting in the living room. "Mom" said to grandma...."Come in here and say hello to your mother." My mom found out about the secret doing geneology about 30 years after my Grandmothers death after talking to a cousin who was the grandson of one of the other sisters.