Relations of Humankind
Until the initial experience of the Jewish nation at the revelation at Mount Sinai (in the year 1312), the sons of Israel—and certainly the generations preceding them—were merely Hebrews not yet G-d’s chosen people. At Har Sinai, not only was there an acceptance of the Torah, but there was also a mass conversion of over sixty myriads of Jacob’s descendants (as well as others; but all proper Jews have the same status anyways, whether they converted or were born into Judaism, because, in essence, every Jew is a descendant of proselytes). Before this mass conversion, there had been no such concept as any person being legally bound by the Torah’s laws, afterwards, there was. While the Jews have their own 613 commandments which G-d gave them in the Torah, G-d only commanded the rest of Humankind to follow the seven (categories of) Noahide laws. Even though there are over twenty forbidden relationships applicable to a Jew, the Rambam only lists six for a gentile man: his mother, his father’s wife, another man’s wife, his maternal sister, another man, and an animal. Each of these sexual prohibitions is learned exegetically from one passage in Bereishis, save for the case of maternal sister, which is learned from Abraham’s encounter with Abimelech.
The holy forefathers and patriarchs of the Jewish Nation, Abraham, Issac, and Jacob, were in essence mere gentiles, and as thus, they were not bound by the Torah, only, the Noahide Laws. Nonetheless, the Talmud implies that the forefathers kept the entire Torah—as any Jew would be required to—from the verse, which states, “Because Abraham listened to my voice, and guarded my safeguards, my commandments, my statutes, and my Torahs”. However, it would seem that many Pre-Sinaitic Hebrews transgressed certain laws as recorded in Scripture, especially laws concerning the forbidden sexual relations. Assuming that the Three Patriarchs accepted upon themselves to keep the Torah, then how could Yaakov have married the two sisters, Rachel and Leah, if marrying two sisters at the same time is regarded as one of the illicit relations as numerated in the Torah? Additionally, according to Rabbi Yehuda, the sons of Jacob were each born with twin sisters, whom they presumably married; such an action surely violates the incest laws. Perhaps to this, one can say that even though one’s maternal sister is forbidden for relations, the sons of Jacob were able to marry their sisters because the twins born with each brother married brothers from a different mother that is permitted. However, this does not answer the question of how Shimon was able to marry his full sister, Dinah, if Simon and Dina were obviously maternal siblings. Furthermore, how can Judah’s marriage to Tamar, his daughter-in-law, be considered a praiseworthy fulfillment of the positive commandment of the Levirate Marriage, if marrying one’s daughter-in-law is clearly forbidden by the Torah? Finally, how was `Amram, the father of Moses and Godol HaDor (“Great man of the generation”), able to marry his aunt if that too is explicitly outlawed in the Torah?
Despite the simple meaning of the verse, Abraham by any means, did not, marry his sister. Sarah, was the daughter of Haran, and her name was given earlier as Yiscah, because she saw (sachsa) the Holy Spirit with Divine Inspiration, and all would gaze (sochin) at her beauty. Abraham called her his sister to both the Pharaoh (of Egypt) and Abimelech (of Philistine) because she was the daughter of his brother, and just like grandsons are considered like sons, so too granddaughters are considered like daughters and she can be called a daughter of Terach, and thus the sister of Abraham.
In defense of Jacob’s marriage to two sisters, the Ramban (Nachmanides, 1194-1270) explains that Yaakov only married them outside of the land of Canaan, but when he arrived to the eventual Holy Land, his favorite wife, Rachel, passed away. This answer reflects the minority opinions of the Ramban elsewhere and (perhaps) Rashi, who believe that Mitzvos are only performed in chutz la’aretz (“out of the land,” i.e. the Diaspora) as practice for the performance of Mitzvahs in Eretz Yisroel. However, according to the majority of halachik deciders (poskim), the obligation to carry out Mitzvas actively applies outside of the Land of Israel just as it applies within. Therefore, one is forced to answer like Rabbi Moshe Isserles (1530–1572) who feels that the verse expounded in the Talmud to prove that Abraham followed the entire Torah applied exclusively to Abraham, and not necessarily to his descendants, so Jacob did not keep the entire Torah. However, this answer is also problematic, for the Midrashei Aggadah say that when Jacob said, “I lived with Lavan”, he meant that he lived a Torah-True lifestyle in the house of Laban, his father-in-law, and kept all 613 commandments. Rabbi Dovid Ben Shmuel Segal (1586-1667) says that Jacob even fulfilled the sacrificial and communal commandments (by learning about them as learning is tantamount to doing). One sees from here that Jacob actually did fulfill all 613 commandments, just as his grandfather did.
Rather, one must answer like Rabbi Moshe Feinstein (1895-1986) who wrote that the forbidden incestuous relationships are only forbidden by way of Kiddushin, which is a legal act of acquisition in which a Jewish man acquires for himself a wife, similar to a betrothal. Since, by definition, a Kiddushin transaction can only take effect if done by a Jew, the Avos (Patriarchs), who had the status of Noahides, were not able to marry with Kiddushin and thus were not bound by the Torah’s rules of illegal marriages in that regard. In a similar vein, the Brisker Rav answers based on the words of Nachmanides that all the forbidden sexual relations in the Torah are only forbidden if done in the fashion of a "Jewish marriage" which only a Jew could perform. Therefore, Jacob, a Jew with the halachik status of a Noahide, was able to follow the entire Torah without being obligated to marry only one daughter of Laban.
Rabbi Chaim Volzhiner (1749-1821) answers that Jacob was able to marry two sisters, and 'Amram, his aunt Jochebed, because they prophetically knew that the world Kabbalistically needed those marriages to exist, and had they not taken place, the Torah would never have been given, and the sole purpose of the world would not have existed. He says that they relied on the fact that the Holy Torah was not yet given in their times and that a Noahide is technically and practically allowed to perform certain marriages which are otherwise forbidden to a Jew. The performance of the Torah's commandments differed before the acceptance of the Torah at Mount Sinai. Rabbi Usher Zelig Weiss writes that Jacob was a prophet and a prophet is allowed to suspend a law of the Torah temporarily. The Talmud relates that on the day of the Future Redemption, HaShem will make a meal for all the Tzaddikim (righteous men) and after the meal, He will ask each of the Avos to lead the grace services, and each will refuse. Jacob's reason for refusal will be that he is not worthy because he married two sisters. This implies that no matter how one can justify Yaakov’s marriage to two sisters, even Jacob himself knew that there is some sort of prohibition involved in his marriage. The reason for this is that even though the ban on marrying two sisters did not apply to Jacob— because he lived before the accepting of the Holy Torah –after the giving of the Torah his actions became retroactively wrong. While when he married them, he was correct in doing so, since the Torah later outlawed his actions, he is not totally exonerated from sin or, perhaps, he is and was just being extra meticulous on himself and deemed himself unworthy, while in fact he really was. Another answering can be offered based on an idea proposed by Rabbi Chaim Shmuelevitz (1902–1979): He writes that before the Siniaitic Revelation, the Noahidic obligation of adhering to one’s words was stronger than any of the Torah’s prohibitions. Accordingly, one can answer that when Jacob told Lavan that he was going to marry Rachel, he was obligated to marry her even after he married Leah, for the responsibility to keep ones word overrides the Torah’s prohibition of marrying two sisters. Rabbi Shmuelevitz continues to explain that this idea was only true before the Siniaitic Revelation, but afterwards, the Torah’s obligations trumps all others.
The Torah says that if a man has relations with his sister, it is a chesed, and he shall be cut off [i.e. executed] in front of the nation. The word chesed typically means "kindness"; however, in this instance, Rashi explains that the word is related to chaisuda, which means "disgrace" in Aramaic. Nachmanides finds difficulty in assuming that the word chesed in this context means something very different from the usage of the word throughout the rest of the Torah. Therefore, Nachmanides explains that even in this situation, the word chesed means "kindness." He explains that the Torah was saying that when a man marries his sister, he is liable for punishment because he should have acted kindly with her by not marrying her because inter-sibling marriages are always destined to fail, and the man was obviously acting of purely selfishness, which is the antithesis to kindness. The Talmud asks why Eve did not die immediately after she ate from the Forbidden Fruit, as punishment for her horrible sin. In asking this question, the Talmud says that Eve's role of companion to her husband Adam could easily have been taken over by Adam and Eve's daughter, whom Adam could have married if Eve died. The Talmud answers that had Adam married his own daughter, Cain would not have been able to marry her, and so the world's population would never have continued. Since Eve was not killed for her sin with the Forbidden Fruit, Cain was therefore able to marry his sister and continue the progeny of the world. The Talmud proves this idea by quoting the verse which states, "I said, 'the world was created through kindness'." The kindness that created the world was the kindness of HaShem by not punishing immediately Eve with death for eating from the Forbidden Fruit. Part of this kindness was allowing Cain to marry his sister and continue the population of the world. From here, Nachmanides understands how marrying one's sister can be called a kindness.
According to Nachmanides, it is only forbidden for a man to marry his sister if it is otherwise possible for the man to do a kindness to her by finding her a suitable match. However, in the case of Cain and his sister, no suitable match existed, as they were the only people in the world, so Cain was legally able to marry his own sister. Rabbi Mordechai Kornfeld says that perhaps this explains how the sons of Jacob were able to marry their own twin sisters. In theory, Jacob would have allowed his daughters to marry foreign men, as long as they converted to the Hebrew religion and accepted certain tenants of belief. However, he saw that all the gentiles wished to remain idol worshippers, and did not want to accept upon themselves the yoke of heaven. Since there were no suitable matches for Jacob's daughters because everyone, save from the Abrahamic family, was idolaters, the sons of Jacob performed a kindness to their sisters by marrying them.
The Maharal (Rabbi Yehuda Loew of Prague, 1525-1609) offers two explanations as to the state of marriage prohibitions before the revelation at Mount Sinai. He explains that because the Avos and their families accepted upon themselves the Torah, even thought they were not required to do so, each person in that family is to be regarded a convert on his/her own right. As such, every convert is like a baby who was re-born and is not related to his previous relatives. Therefore, Rachel and Leah were not considered sisters, so Jacob was permitted to marry both; no children of Jacob were considered siblings, and thus the boys were able to marry the girls. Judah was not regarded as the father of Er and Onan, so Tamar, their wife, was not his daughter-in-law. Amram and his aunt, Jochebed, were not really related either, so their marriage was perfectly legal. However, the Maharal points out that the generation of the exodus from Egypt was considered “forced converts” because HaShem raised Mount Sinai upon them and forced them to accept the Torah, and thus they retained their former relatives. Rabbi Yitzchok Hutner (1906-1980), the Warsaw Illui (prodigy) and Rosh Yeshiva of Yeshivas Rabbi Chaim Berlin, explained that when one is forced to convert, he does not experience a change in mental attitude, so he is actually the same person as before, whereas a willing convert becomes a new person. However, this is usually not applicable in practice because Judaism –unlike other religions—does not carry out forced conversion.
The Maharal offers an additional understanding. Since the Torah was not yet given to Jacob, Jacob only had his prohibitions through the mouth of G-d, and if G-d told him through Ruach HaKodesh (a form of prophecy) that he was supposed to marry two sisters, then the only factor stopping him was another directly commandment from G-d’s mouth and the latter can supersede the former. There is a dictum in the Talmud, which states, “the mouth that prohibits is the mouth that permits.” He also concludes that the ancestors of the Jewish Nation then did not keep any negative commandments when it interfered with a positive commandment, and they exclusively performed the positive commandments as instructed to by the Torah. The Maharal of Prague also cites numerous examples through rabbinic literature in which the predecessors of the Jewish nation specifically carried out positive commandments (such as Shabbos/Sabbaths, Shechita/ritual slaughters, Terumah/tithes, and Yibbum/levirate marriages), but not negative ones. However, this explanation of the Maharal is difficult to digest in light of the words of his cousin, the Maharsha: the Mishnah says that Abraham carried out the entire Torah, and Rav said that Abraham fulfilled the entire Torah and. On this, Rabbi Akiva Eiger asked why Rav echoed the words of a Mishnah, which predated him. Rabbi Shmuel Edels (1555–1631), the Maharsha, answered that the Mishnah refers specifically to the positive commandments, which Abraham carried out, but Rav was referring to the fact that he even fulfilled the negative commandments.
The Ramban discusses how Judah, the son of Jacob was able to marry his daughter-in-law and have such a marriage be called an ideal fulfillment of the Levirate Marriage. He explains that the nature of the Levirate marriage is rooted in a deep mystical secret. As explained elsewhere in the Ramban, the soul of the deceased is reincarnated into the soul of his widow’s new child fathered by his relative. This practice, says the Ramban, is an ancient tradition that actually pre-dated the giving of the Torah, and it is an innate practice of human natural decency; in fact, he says, it is called cruel for a man to refuse the hand of his brother’s widow in marriage. Actually, in addition to the Israelites who carried out this ritual, (the Samaritans, the Karaites,) the Xiongnu, the Mongols, the Hindus, and the Tibetans also practiced the Levirate marriage in a similar way to how the Torah prescribed it. The right to perform the Levirate marriage does not exclusively belong to the deceased’s brother, but rather it is a sort of inheritory right. In a situation where the brother refuses to do the marriage –or in the case of Shelah, son of Judah, where the levir is too young to perform the required act of intercourse –the right would be inherited by the next closest relative, and in the case of Tamar, that next relative was the father of the deceased, Judah.
Under normal circumstances, no close relative of the deceased can really marry the widow because she is considered an ervah (“[forbidden] nakedness”) to them, however in the case of the brother of the deceased; the Torah gives special permission for the performance of Yibbum. This is because HaShem specifically wanted the brother to perform Yibbum and not any other relative because the Cabbalistic outcome is greater, and simply because it was more common for a brother-in-law to perform the marriage (as Onan did) than for a father-in-law (like Judah) to do so. This also explains why the actions of Boaz in his marriage to Ruth can be called Yibbum; he was the closest living relative willing to marry her. The simple explanation of Judah’s marriage should be that he acquired his daughter-in-law as a wife through a legal means with his initial intercourse with her even though it was unintentional. This is because a Yibbum can effectively create a marriage even if the marital relations done were by mistake as explained in the Mishna. Obviously, Judah had no idea that he was cohabitating with his daughter-in-law when he met a harlot on his way to Timnah to shear his sheep (as a form on consolation on his recent loss of his wife Shua). Rashi explains that since Tamar covered her face modestly while she was in Judah’s house as his son’s wife, he did not recognize her when she dressed as a prostitute at the crossroads. This shows that he surely had no clue as to her identity when he was performing the sexual relations with her. In the end, however, when he realized that she had been the one whom he was with and that is how she became pregnant, he ceased living with her. The Ramban explains that he did so despite the fact that they were totally considered married. He seemingly did so as a sort of self-piety because he believed to be sinning when in fact, he was marrying his Intended anyways. However, the Midrash says that Judah was the man who instituted the idea of a Levirate marriage, so he seemingly was not just performing an age-old ceremony.
Rashi has an intricate method of explaining how Judah was able to perform the levirate marriage upon Tamar if the latter was prohibited to him because she was his daughter-in-law. A marriage of a minor girl is not effective biblically unless her father married her off. In order to avoid having a problem of indecency with unmarried minor orphans, the Rabbis decreed a rabbinical marriage for such girls. However, because the effectiveness of the marriage is only Rabbinical not Biblical, before the girl becomes a legal adult, she has the option to do miyun (refusal) to her husband and thereby retroactively annul her marriage. Rashi proves that Tamar was an orphaned minor (assuming that her father was not Shem son of Noach) and that she performed miyun. Therefore, it became that she retroactively never married Judah’s two sons Er and Onan, and therefore she never had the prohibition of daughter-in-law to Judah.
When HaShem commanded the Jews to be careful in extra relations, besides those normally forbidden to any human, they began to cry (this is the explanation of the crying in Numbers 11:10). Rav Chisda said that before Israel sinned with the forbidden relations, the Holy Presence (Shechinah) rested with each Jew as it says in the verse, “For HaShem, your G-d, walks in the midst of your camps”. However, after they began to sin with the forbidden relationships, the Shekhina of HaShem removed itself from them as it says, “[S]o that He shall not see a shameful [naked] thing among you, and turn away from behind you”. With the will of G-d, the Holy Presence should return to His Holy Nation and to the Holy Temple, may please it be built speedily and in our days: Amen.
 The Anglicized version of the word, Ivrim, meaning “Crossers” because they crossed the Euphrates River
 Makkos 23b
 Avodah Zarah 64a
 see Leviticus 18:6-20, 18:22-23, and 20:10-21
 Maimonides, Laws of Kings 9:5
 Although the prohibitions are given in the form of whom a man is forbidden to cohabit with, the converses are always true, so the female has a prohibition whenever the man has one.
 The Maimonides’ enumeration, by all means, is not accepted by everyone. The Kesef Mishna (Maran Rav Yosef Ben Efraim Karo, 1488-1575) points out (ad loc.) that the Maimonides decided the Halacha according to Rabbi Akiva (of Sanhedrin 58b), but according to Rabbi Eliezer (Ibid.) one’s father’s sister and mother’s sister should also be prohibited. Indeed the Sefer HaMizrachi (written by Rabbi Eliyahu Mizrachi, 1455-1526) says (Genesis 46:10) that we follow the law of Rabbi Eliezer in the case of a father’s maternal sister. Additionally, to the list of Maimonides, the Lechem Mishneh adds one’s own daughter (Sanhedrin 58b, second version of Rav Huna’s statement). The Ritva (Rabbi Yom Tov ben Avrohom Alshevili, circa. 1300) seemingly argues (Yevamos 98b) on Maimonides' view and permits a non-Jew to marry his father’s wife. However, such an opinion contradicts the Talmud (Sanhedrin 58b) which proved otherwise from the fact that had Adam lain carnally with his daughter, she would have been prohibited to Cain under the prohibition of “father’s wife”, and thus the world’s population would never have successfully propagated. Cain himself has a special exemption on the rule against marrying one’s sister due to the verse (written prophetically by Abraham under the pen name “Ethan the Ezrahite,” Bava Basra 14b) which says, “For I said, ‘Forever will kindness be built’” (Psalms 89:2). Adam’s abstinence from relations with his daughter was deemed a gracious act, and upon that act of kindness, the world founded.
 Genesis 2:24
 See Genesis 20:12, where Abraham implies that had Sarah been his maternal sister, he would have been prohibited to her.
 Yoma 28b
 Genesis 26:5
 See Leviticus 18:18
 Midrash Rabba, Genesis Rabbah, 84:19
 See Rashi to Genesis 46:10
 See Genesis 29:33 where Leah begets Simeon and Genesis 30:21 where she births Dinah
 Deuteronomy 25:5-10, whereby the widow of a childless man marries her husband’s brother; levir means brother-in-law in Greek
 Leviticus 18:15
 see Sotah 12a
 Exodus 6:20
 Leviticus 18:12 outlaws marrying one’s father’s sister
 Genesis 20:12
 Genesis 11:29
 Megillah 14a
 Commentary to Leviticus 18:25
 Deuteronomy 11:18
 Responsa ReMa, §10
 Yoma 2b
 Genesis 32:5
 The basis for this is because the numerical value of the Hebrew word for “I lived”, garti, equals 613, which is an allusion to the 613 Commandments stated in the Torah.
 Divrei Dovid, ad loc.
See responsa Iggress Moshe, Even HaEzer §4:9
 Chiddushei HaGriz al HaTorah
 Chiddushei HaRamban to Yevamos 91a
 Nefesh HaChaim 1:21
 See Responsa Rashba Volume 1 §92, Responsa Radbaz §696
 Minchas Usher Genesis §42:5
 See Ohr HaChaim to Genesis 49:3
 See Maimonides' introduction to Commentary on the Mishnah
 Pesachim 119b
 Sichos Mussar, Shaarei Chaim, Ma’amar 30 based on the Aurch L’Ner to Sukkah 53a
 Leviticus 20:17
 See Targum Onkelos ibid. and to Genesis 34:4
 Ramban to Leviticus 20:17
 Sanhedrin 58b
 Because she would have been his father's wife
 Her name is given in various sources as Kalmana (see Seder HaDoros, and Abrabanel to Genesis 4:1), Lebuda, and Awan (in the Christian New Testament Book of Jubilees)
 Psalms 89:3
 Kedoshim, 5757
 Ra'avad to Avodah Zarah 36b
 Gur Aryeh, Bereishit 46:10
 See Yevamos 22a
 This is contrary to the belief of the Ohr Somayach, (Rabbi Meir Simcha HaKohen of Dvinsk, 1843-1926), who wrote in Meshech Chochmah, Deuteronomy, 5:27 that the marriage of Amram and Jocheved is a proof that the generation of the exodus has the status of converts.
 See also the introduction to Shuv Shmaytsa, letter Ches, by Rabbi Aryeh Leib HaKohen Shain Heller (1745—1813), who also authored the Ketzos HaChoshen, and Avnei Milluim.
 According to the Ritva (Kiddushin 22a) in the case of an aishes yifas to`ar (“woman of beautiful form” who was taken captive in a war, as described in Deuteronomy 21:10-14) the woman (and her child from the Jewish soldier) are forced to convert even if they choose not to. However, Tosafos (Yevamos 48a) disagree and rule that such a woman cannot be forced to convert. One instance of this situation was the wife of Dovid HaMelech (King David), the daughter of King Talmai of Geshur, Achinoam, and originally begat Tamar (who was later raped by her half-brother Amnon) from their first intercourse (while Achinoam was still a gentile), and later had Absalom (after she converted).
 Just like a positive commandment can displace a negative commandment in the Torah in certain instances, see Yevamos 4a-7b
 Kiddushin 82a
 Yoma 28b
 Gilyon HaShas to Kiddushin 82a
 Chiddushei Maharsha to Yoma 28b
 To Genesis 38:8
 Job, Chapter 30
 She was the widow of his first cousin, who was the son of Elimelech, brother of Boaz’s father, Salmon.. Elimelech and Salmon were sons of Nahshon son of Amminadab who is famed for having been the first to jump into the Red Sea, and was the brother of the wife of Aaron, Elisheva, who was also the daughter of Aminadav.
 See Book of Ruth
 Yevamos 6:1
 Genesis 38:15
 Genesis 38:26
 Genesis Rabah 85:5
 Sotah 11a
 See Ya’avetz ad loc. who elaborates on the understanding of Rashi in light of the Biblical laws of Yibbum as described in Yevamos.
 Yoma 75a
 Sotah 3b
 Numbers 23:15