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Prohibited Sexual Relationships

Jewish law forbids a number of sexual relationships beyond incest and adultery.

Jewish law forbids a number of sexual relationships, the foremost of which is adultery — defined as a married woman having sex with a man who is not her husband and the only sexual relationship prohibited in the Ten Commandments. The bulk of other biblically prohibited sexual relationships are found in Leviticus 18, which includes a detailed list of them, the majority either incestuous or cases of a man having sexual relationships with women who are closely related to one another. Leviticus 18 also forbids bestiality, sex with a menstruating woman and male homosexual sex

The category of sexual transgressions is referred to in Hebrew as giluy arayot, literally “uncovering nakedness.” This phrase derives from the language in Leviticus 18, which states in most of these cases that one is forbidden to “uncover the nakedness of” the forbidden partner. 

Specific Forbidden Unions

Leviticus 18 explicitly bars sexual relations between a man and his …

  1. Mother
  2. Stepmother
  3. Sister
  4. Half-sister
  5. Granddaughter
  6. Stepsister (via father’s wife)
  7. Father’s sister
  8. Mother’s sister
  9. Father’s brother’s wife
  10.  Daughter-in-law
  11.  Brother’s wife

The Torah also forbids a man to engage in sexual relations with two women who are closely related. These include:

  1. A woman and her daughter
  2. A woman and her granddaughter
  3. A woman and her sister (while they are both alive)

Finally, the text forbids sex with a woman who is menstruating, a married woman, between two men, and between a man or woman and an animal. In two cases — the general prohibition on sex with “anyone of his own flesh” (i.e. a close relative) and the prohibition on sex with a menstruating woman — the text forbids one even to “come near” to uncovering nakedness. This prohibition is generally understood to bar various forms of intimate contact that might lead to sexual intercourse. 

The language of these verses is clearly addressed to men, but the relationships they forbid are understood to apply to both partners. 

Additional Relations Prohibited by the Rabbis

Later rabbinic authorities added further prohibitions to those enumerated in the Bible. Several of these concern additional relatives one is forbidden to have sex with, including grandparents and great-grandparents. 

Lesbian sex, which is nowhere mentioned in the Torah, was explicitly prohibited by medieval rabbinic authorities on the basis of an opinion recorded in the Talmud (Yevamot 76a) that women “who rub against each other” (some translate this as “playing around”) cannot marry into the priesthood. Both Maimonides and Rabbi Joseph Caro (author of the Shulkhan Arukh) prohibit such activity outright.  

Maimonides also prohibits sex between unmarried people, explicitly rooting this law in the Torah’s prohibition (Deuteronomy 23:18) against harlotry. Though this position was not universally held even in Maimonides’ time, it has become the standard among Orthodox Jews today. The liberal movements have taken a more permissive approach. Rabbi Elliot Dorff, one of the foremost Jewish law authorities in the Conservative movement, has suggested that while marital sex remains the Jewish ideal, non-marital sex is a reality for many Jews and should be undertaken only in accordance with the same values of as marital sex: honesty, modesty, love and holiness.

The Conservative movement has also taken steps to liberalize its approach to male homosexual relationships. In 2006, the movement approved a responsum upholding what it understood to be a biblical ban on anal sex between men and affirming heterosexual marriage as the Jewish ideal. However, the movement reversed rabbinic bans on gay sexual activities short of anal intercourse, reaffirmed the full inclusion of gays and lesbians in Jewish life, endorsed welcoming gay and lesbian Jews into the rabbinate and opened the door to religious celebrations of committed gay partnerships. In 2012, the movement approved marriage and divorce procedures for same-sex couples.

Reasons for the Prohibitions

The Torah does not offer any explicit reasoning for barring most of these relationships, but the listing of prohibitions in Leviticus 18 is preceded by a warning about emulating practices of the peoples of Egypt and Canaan. At the conclusion of the list, the text makes this statement:

But you must keep My laws and My rules, and you must not do any of those abhorrent things, neither the citizen nor the stranger who resides among you; for all those abhorrent things were done by the people who were in the land before you, and the land became defiled. So let not the land spew you out for defiling it, as it spewed out the nation that came before you. All who do any of those abhorrent things—such persons shall be cut off from their people. (Leviticus 18:26-29)

The language in the final verse, that offenders of these rules shall be “cut off,” is a reference to the biblical punishment known as karet, or excision, the exact particulars of which are somewhat unclear. The suggestion here is that these practices were common to the peoples who lived in the land before the arrival of the Israelites and that their continued presence in the promised land is dependent on not doing the same. Two chapters later, in Leviticus 20, the text specifies a different punishment, death, for several of these same transgressions. Neither of these punishments are still carried out today. 

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