who was not conceived in sanctity, as his parents were still gentiles, but his birth was in sanctity, as his mother converted before his birth, he has maternal kinship, i.e., his relationship to his mother’s relatives is recognized, but he does not have paternal kinship.

How so? If he married his maternal half sister, who was born before him and converted, he must divorce her. Although by Torah law they are considered unrelated, as a convert is considered to be reborn and all his previous family relationships are disregarded according to halakha, the Sages prohibited their marriage, lest he think that as a Jew it is permitted for him to engage in behaviors that were previously forbidden to him. If she is his paternal half sister, he may maintain her as his wife, as it is permitted for a gentile to marry his paternal half sister. If he married his father’s maternal half sister, he must divorce her. If he married his father’s paternal half sister, he may maintain her as his wife.

If she is his mother’s maternal half sister, he must divorce her. If she is his mother’s paternal half sister, Rabbi Meir says he must divorce her, and the Rabbis say he may maintain her as his wife. As Rabbi Meir would say: With regard to any forbidden relative who is forbidden due to maternal kinship, whether the woman is his paternal relative, e.g., his father’s maternal half sister, or his maternal relative, he must divorce her; whereas if she is forbidden due to paternal kinship, he may maintain her as his wife.

And according to all opinions, he is permitted to marry his brother’s wife and his father’s brother’s wife, and all other relatives with whom relations are forbidden in the case of born Jew are also permitted to him. The expression: And all other relatives with whom relations are forbidden, is added to include his father’s wife, who is permitted to him if she was widowed or divorced from his father.

With regard to a gentile who married a woman and her daughter and they all converted, he may marry one but must divorce the other one; and he should not marry the second of them ab initio. If his wife, the daughter, died, he is permitted to maintain his mother-in-law as his wife. And some say that he is prohibited from maintaining his mother-in-law. In any event, Rabbi Meir clearly holds that several forbidden relationships for which a Jew is not liable to receive capital punishment, but only karet, are forbidden to descendants of Noah as well, namely, intercourse with one’s sister or one’s parent’s sister.

Rav Yehuda says: This is not difficult; this baraita cites the statement of Rabbi Meir according to the opinion of Rabbi Eliezer, and that previously mentioned baraita cites the statement of Rabbi Meir according to the opinion of Rabbi Akiva.

As it is taught in a baraita with regard to the verse: “Therefore a man shall leave his father and his mother, and shall cleave to his wife, and they shall be one flesh” (Genesis 2:24), that Rabbi Eliezer says: “His father” is referring to his father’s sister, i.e., one must abandon the possibility of marrying his father’s sister and marry someone else. “His mother” is referring to his mother’s sister. Rabbi Akiva says: “His father” is referring to his father’s wife; “his mother” is referring to his mother, literally.

“And shall cleave to his wife,” but not to a male; such a relationship is not defined as cleaving. “To his wife,” but not to the wife of another man. “And they shall be one flesh” indicates that he should marry one of those with whom he can become one flesh, i.e., they can bear children together. This excludes domesticated and undomesticated animals, with which one is prohibited from engaging in bestiality, as they do not become one flesh. All these are forbidden to the descendants of Noah.

§ The Master said in this baraita that Rabbi Eliezer says: “His father” is referring to his father’s sister. The Gemara asks: Why not say that it is referring to his father, literally, prohibiting homosexual intercourse with one’s father? The Gemara answers: This prohibition is derived from another phrase in the verse: “And shall cleave to his wife,” but not to a male; this includes his father.

The Gemara asks: Why not say that “his father” is referring to his father’s wife? The Gemara answers: This prohibition is derived from the term “to his wife,” but not to the wife of another man. The Gemara asks: Why not say that it is referring to his father’s wife after his father’s death, when she is no longer a married woman? The Gemara answers: The term “his father” is interpreted in a way that is similar to the interpretation of the term “his mother.” Just as his mother is not forbidden due to her marriage to his father, but rather due to her relationship to him, so too, the term “his father” is not referring to a relative who is forbidden to him due to her marriage.

Rabbi Eliezer says that “his mother” is referring to his mother’s sister. The Gemara asks: But why not say that it is referring to his mother, literally? The Gemara answers: This prohibition is derived from the term “to his wife,” but not to the wife of another man; and his mother is his father’s wife. The Gemara asks: But why not say that it is referring to his mother after his father’s death, when she is no longer married? The Gemara answers: The term “his mother” is interpreted in a way that is similar to the interpretation of the term “his father.” Just as the term “his father” is not interpreted literally, so too, the term “his mother” is not interpreted literally.

Rabbi Akiva says: “His father” is referring to his father’s wife. The Gemara asks: But why not say it is referring to his father, literally? The Gemara answers: That prohibition is derived from the term “and shall cleave to his wife,” but not to a male. The Gemara challenges: If so, the prohibition of his father’s wife is also derived from another term: “To his wife,” but not to the wife of another man. The Gemara explains: The term “to his wife” is referring to his father’s wife after his father’s death, when she is no longer married.

Rabbi Akiva says: “His mother” is referring to his mother, literally. The Gemara challenges: That prohibition is derived from the term “to his wife,” but not to the wife of another man. The Gemara explains: According to Rabbi Akiva, the term “his mother” is referring to his mother whom his father raped, i.e., she was never his father’s wife.

With regard to what principle do Rabbi Eliezer and Rabbi Akiva disagree? Rabbi Eliezer holds