Forbidden relationships in Judaism

Forbidden relationships in Judaism (איסורי ביאה Isurey bi'ah) are those intimate relationships which are forbidden by prohibitions in the Torah and also by rabbinical injunctions. Some of these prohibitions—those listed in Leviticus 18, known as arayot (Hebrew: עריות‎‎)—are considered such a serious transgression of Jewish law that one must give up one's life rather than transgress one of them. (This does not necessarily apply to a rape victim.) This is as opposed to most other prohibitions, in which one is generally required to transgress the commandment when a life is on the line.

Adultery is prohibited by the seventh of the Ten Commandments (Exodus 20:12) which says simply:

It is forbidden for a man to have sexual relations with a married woman not his wife. (Leviticus 18:20, 20:10)

A man is not allowed to have sexual relations with a woman—including his wife—during and after her menstrual period (Leviticus 18:19), until after she undergoes the proper cleansing procedures in a mikveh. Such a woman is referred to as niddah.

Religious intermarriage is forbidden in Judaism. There are differing opinions among the rabbis as to when the prohibition on sexual relations with non-Jews is from the Torah and when it is rabbinic.

Sexual relation with certain close relations are forbidden. Though they are generally called incestuous relations, the biblical list does not necessarily correspond to those prohibited under state laws. The prohibited relations are:

In addition to the relationships biblically prohibited to Jews, rabbis have gone further to prohibit certain additional relationships with various blood relatives and in-laws. These are called "Shni'ot" (secondary prohibitions). Some of these are:

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