When did Judaism begin to condemn lesbianism?
This Torah passage, we are told, is glossed as a reference to lesbianism. Closer examination of the text reveals a different story. Here is what the midrash actually says: “And what did they do? One man marries another man, a woman marries a woman, and a man marries a woman and her daughter, and a woman marries two [men].”
The disapproval expressed in this Sifra passage is not directed against sexual conduct, but at four types of marriage: male-male, female-female, marriage of a man jointly with a woman and her daughter, and polyandry. (Note that polygyny, where one man takes several wives, was not opposed; it was normal in the Jewish world at the time.) An odd feature is the neglect of the one Egyptian practice that was in fact anomalous: brother-sister marriage.
We pause to note an intriguing possibility. As a rule one does not attempt to prohibit a practice that is rare or unknown, such as eating chalk or old newspapers. What is prohibited is behavior that is actually happening. Our society, for example, has unfortunate laws against the use of marijuana, not because of some remote possibility that someone, sometime might resort to the practice, but because people are actually doing it. The authorities want them to stop.
Political circumstances in the later Roman empire, when the midrash appeared, were notoriously turbulent. Under those circumstances it is possible that two Jewish men or two Jewish women might form a marriage-like union for mutual support and protection. As far as I know, this possibility has not been investigated.
Still, the main point about this midrash is that it deals only with forbidden forms of marriage, including marriage of women with women. It does not, as has sometimes been claimed, condemn sexual relations between women as such.
Passages occasionally cited from the Talmud are even less helpful. The ban on lesbian relations is clearly of later origin. The prohibition is sometimes traced to Maimonides (1135-1204), who (it is claimed) stipulated whipping as a punishment for lesbian conduct. However, Maimonides is also quoted as saying that the disapproval of female-female sexual relations reflects neither a biblical or rabbinical prohibition.
When then did the condemnation of lesbianism appear in Jewish tradition? So far I have not found any definitive answer to this question. The consolidation of the prohibition seems to have been a gradual process effected in relatively modern times.
Why did this process take place? First, there seems to be a tendency to analogize with male homosexuality, which is clearly condemned in Leviticus 18 and 20. However, the absolute parallel between lesbianism and male homosexuality--so often taken for granted nowadays--is relatively recent, dating from the second half of the nineteenth century.
My tentative conclusion is that the Jewish prohibition of lesbianism is an importation from non-Jewish, specifically Christian sources. In the later middle ages some scholastic sources condemned lesbianism. Beginning in the sixteenth century there is evidence of popular prejudice against female-female sexual relations.
Historically, normative Judaism (which began to take form in the third century C.E.) has been shaped both by opposition to, and imitation of Christianity. The prohibition of lesbianism would appear to be an instance of imitation.