#43. Is it lawful to marry your sister OR not? (Gen 20:12 vs Lev 18:11, 20:17)


Customs, beliefs, and worldviews change, and with them so too laws—no mystery here. But when we have a so-called “Book” that in actuality is a collection of the laws and narratives that reflected the customs, beliefs, and worldviews of a people (and peoples!) spanning approximately 1,000 years, contradictions are bound to occur. There should be no mystery here either.

Thus, reflective of archaic customs shared throughout the ancient Near East, the older Yahwist and Elohist traditions have no qualms about informing its audience that Abraham’s wife, Sarah, is in fact his sister. And Genesis 20:12 further specifies that Sarah was his sister on his father’s side. Even though these stories were written down circa the 9th-8th centuries BC, they most likely reflected archaic views and customs. Certainly marrying one’s father’s daughter, or any close relative, would have been established norm, especially for many aristocratic or royal families.

Our point is that this was all to change, of course. The 6th c. BC Priestly writer of Leviticus, for example, seems to reflect this by sternly prohibiting such customs. The laws that the Priestly writer himself wrote or preserved, since they may well have been part of the tradition that he himself inherited, are all prefaced by the formula “And Yahweh spoke to Moses saying. . .”

The nudity of your father’s wife’s daughter, born of your father—she is your sister; you shall not expose her nudity. (18:11)

And a man who will take his sister, his father’s daughter or his mother’s daughter, and see her nudity, and she will see his nudity, it is shameful. And they will be cut off… (20:17)

“Exposing one’s nudity” not only was a euphemism for sex, but in all likelihood marriage as well. These two laws or prohibitions probably come from 2 different sources, and were redacted together in the book of Leviticus. Many of the laws penned by the later Priestly writer were done in an attempt to preserve Israelite identity. If, for example, the Priestly guild was composing its text while in exile in Babylon, then penning laws that banned those very customs followed by Israel’s neighbors, such as the Babylonians, would certainly have gone a long way in forging Israelite identity during this historical crisis.

In sum, it seems safe to conclude that the different attitudes expressed between the earlier traditions preserved in Genesis and the later ones of the book of Leviticus express the changing customs and views of mankind rather than those of a god or Yahweh.

12 thoughts on “#43. Is it lawful to marry your sister OR not? (Gen 20:12 vs Lev 18:11, 20:17)

  1. Dan: Even in an Adam and Eve scenario, you would only need to allow the incestuous relationship 2 times(2 sons marry 2 daughters only). After that the grandchildren would not need to do that.

    So the whole “assumption” of not enough people is not a strong argument at all.

  2. Is it possible that the author(s) simply showed that prior to the law of Moses, sibling marriage was allowed until this allowance ended when the law was given to Israel by Yahweh in which case there is no contradiction in text and the story flow doesn’t contradict.
    Even to say that god was contradictory in standards is a bit weak, as it can be assumed he allowed sibling marriage for a time when there wasn’t enough humans on the planet and theologically can be assumed that he put an end to sibling marriages once he established law covenant with the nation of Israel when the human numbers were assumably large enough.
    From the textual flow, I really don’t see a contradiction unless there is textual allowance for sibling marriages under the law covenant or forbiddance of sibling marriage prior to that law covenant – which there isn’t.

  3. Still circular. “In this case the Yahwist text is older than the priestly” is an assumption made without empirical evidence since we’re not talking about a mere 7th century date for Deuteronomy but for authorship of the Tanakh as a whole. And surely you’re not saying the Qumran Torah is missing Deuteronomy entirely when it is portions and not a complete scroll to begin?

    1. The assumption made is whoever authored, wrote down, the Abraham-Sarah story in Genesis had no problem with the wife-sister marriage thing. Whoever wrote down, authored, Leviticus 18 vocalized adamantly against this and similar “impurities.”

  4. But this “contradiction” is circular, isn’t it? “There are Yahwist and Priestly authors, and the one tolerates the relationships, and the other doesn’t.” But I’ve heard ten-year-olds make this apologetic, “Incest was lawful before the Law of Moses.” That’s the order in the ancient scrolls–Leviticus has always followed Genesis. It’s no more a contradiction than saying gay marriage is unlawful in a state before that state changes its codes of law.

    There’s no empirical evidence, is there, that Deuteronomy was a later addition to the Torah, is there? The Jews have had these scrolls since time immemorial. Isn’t all of this textual speculation only? Is there a Torah from the Qumran community or the Dead Sea region that is one “book” short in the scroll?

    1. No. I would not think so. Your starting from a premise I am not—i.e., taking the narrative chronology at face value. It’s naive to think that the texts of the Bible were written in the order of how the books of the Bible now stand. Indeed, in this case the Yahwist text is older than the Priestly. But again, I’m not comparing 2 points in time, and those 2 points are part of the fictional narrative. Like I said, this is not a typical example of a textual contradiction.

      The empirical evidence comes from the textual data of the Bible itself. Why and how scholars think the Deuteronomist was a later text — I offer a brief summary in How the Bible was discovered to be a collection of contradictory texts — one of the sections near the end. It is a hypothesis that best explains the textual data. In short, the laws propounded in Deuteronomy, which were said to be given in the Mosaic past, are not acknowledged or apparently know or mentioned in the books of Samuel, Kings, pre-exilic prophetic literature, etc. They only come into play with Josiah in the 7th c. BC and in post-exilic literature.

      There are parts of a Torah from the Qumran community, and those texts also exhibit differences from the Babylonian recension, the version we have.

  5. Why should we look as far as the distance between Genesis and Leviticus? Moses himself was the product of such a marriage against the Law! Occam’s Razor says this kind of marriage was prohibited as one of the many commandments the Israelites received in the wilderness which the patriarchs did not have. The Law’s author is honest in stating Moses’s origins. The “contradiction” would come if there were incestuous marriages after the Law was enacted, right? I don’t “get” this one…

    1. Matt, I see you’ve been perusing the site. Welcome. There are a variety of different types of contradictions on this site. This one is certainly not typical. I’ve included it because it does share an essential feature with many other contradictions here—it too is the result of conflating textual traditions, each one written in a different time period and advocating its own unique set of beliefs and worldviews. So here it would seem that one textual tradition, the Yahwist, had no problem with wife-sister relationships, while the later Priestly tradition was certainly adamant about condemning such practices.

      At any rate, this “contradiction,” as with others, is not so much the difference between two points of time in the composite text’s narrative chronology (Genesis to Sinai), but rather between two different historical eras, circumstances, and audiences that prompted the writing of these two traditions: that of the 9th-8th century BC Yahwist and the 6th century BC Priestly writer. They themselves, or the cultures or elite guilds they represented, shared contradictory ideas on the topic, at least according to what the texts seem to imply. That seems to be my point here.

      What gets more dicey, is when the 7th century BC Deuteronomic text starts to condemn all the kings of the north for not following Yahweh’s laws as the narrative tradition claimed where revealed to Moses at Sinai in the archaic past. But in fact they were a creation of the 7th c. Deuteronomist who retrojected these innovative laws into the archaic past! Thus the Deuteronomist actually used 7th c. laws to condemn kings living in the 9th -8th centuries! Nothing short than the power of literature!

  6. The same commentators who try to make Sahar “Iscah” also play games with Keturah to make it Hagar (keturah means insence, so he returned to the sweet smell of his youth – Hagar”), which has problems of its own.

  7. Hmmm…looks like I didn’t get that link to work. Anyhow, here is the pesky sentence, where they need to make Sarah the daughter of someone else by saying that “Iscah” (Genesis 11:29) who was the daughter of someone else was also Sarah (although you have to mangle the name to make it work in the Midrash, which is often the case with Midrashim). Here is that text:

    “…the name of Nahor’s wife Milcah, the daughter of Horan, the father of Milcah, and the father of Iscah. Whereon Rabbi Isaac observed: Iscah was Sarai, and why was she called Iscah? Because she foresaw [the future] by holy inspiration;…”

  8. Nice catch. It also goes against the Jewish tradition that “The Patriarchs kept all of the Torah”, which would halt any “But, it was before Mt. Sinai” gambit. There are those who say “No, she was his cousin” based on some verbal manipulations and a bit of Midrashic exegesis in the Talmud <A HREF="(Sanhedrin 69b)" http://www.come-and-hear.com/sanhedrin/sanhedrin_69.html that says she was his uncle’s daughter, and for that to work, you have to reinterpret “father” as “uncle” into a later passage, which also has problems. So yes, I would give this one a thumbs up.

    1. Interestingly, P’s brief genealogy in Genesis 11:27-32 already seems to be distancing Sarah as Abraham’s sister. Unlike the wife of Abraham’s brother Nahor, Sarah is not given a genealogy, and then later only mentioned as Terah’s daughter-in-law. Surprisingly too, the Chronicler, while mentioning Abraham’s later wife Keturah twice, never mentions Sarah! It would seem that the later midrashic re-interpretation which you mention already started to take place in some of the Bible’s late compositions.

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