Yevamot 97B

״אח מאב ולא מאם, והוא בעלה דאם, ואנא ברתה דאנתתיה״. אמר רמי בר חמא: דלא כרבי יהודה דמתניתין.

§ The opinion that a man may marry a woman raped or seduced by his father can lead to the existence of an unusual family relationship. A woman says: I have a half brother from my father and not from my mother, and my half brother is the husband of my mother, and I am the daughter of his wife. Rami bar Ḥama said: This state of affairs is not legitimate according to the opinion of R' Yehuda in the Mishnah, who holds that a man may not marry a woman with whom his father had sex, even if they were not married. However, according to the Rabbis, a woman whose father was not married to her mother can legitimately have a paternal half brother who is married to her mother.

״אח הוא, וברי הוא, אחתיה אנא דהאי דדרינא אכתפאי״⁠ — משכחת לה בגוי הבא על בתו.

The Talmud cites another riddle about a bizarre family relationship. A woman says: He is my brother and he is my son; I am the sister of this one, whom I carry on my shoulders. What is the solution? You find it in the case of a non-Jew who had sex with his daughter, and she bore him a son, who is therefore both her brother and her son. The Talmud is referring to a non-Jew because it does not wish to entertain the idea that a Jew would act in such a manner.

״שלמא לך ברי, בת אחתיך אנא״⁠ — משכחת לה בגוי הבא על בת בתו.

The Talmud cites another riddle: Peace upon you, my son; I am the daughter of your sister. You find the solution in the case of a non-Jew who had sex with the daughter of his daughter, who bore him a son. This son’s mother is related to him from her mother’s side as well, as she is his sister’s daughter.