Rabbi Akiva asked Rabban Gamliel: if a person has sexual relations with his sister (incest), and that same sister is also his aunt on his mother’s side and his aunt on his father’s side — does he need to bring one sacrifice for atonement or three sacrifices? What are the issues under debate? On one hand, since it a single act of sexual intercourse, with a single woman, one sacrifice should be enough to atone for the act of sexual misconduct. On the other hand, since he transgressed three prohibitions with a single act — he had sexual intercourse with his sister, with his maternal aunt, and with his paternal aunt — he should have to bring three sacrifices to atone for the three sins. Rabban Gamliel answered Rabbi Akiva and said that he had never heard an explicit teaching on this matter, but that in his opinion the man should bring three sacrifices. How could there be such a case, in which a woman is simultaneously his sister, the sister of his father, and the sister of his mother? Answer: A man had sexual relations with his own mother, and from this act two daughters were born. Afterwards that man had sexual relations with one of the daughters and she gave birth to a son. This son then had sexual relations with the other daughter, who is simultaneously his father’s sister, his mother’s sister, and his own sister.
(Babylonian Talmud, Tractate Makot 14a)