Scattered, inconclusive remarks on the prohibition of brother-sister incest in Leviticus 18 and 20.
A number of the relations prohibited in these chatpers recall relationships that existed among the patriarchs. Leviticus 18:11 prohibits a man from taking his half-sister, the daughter of your father. That is exactly the relationship of Abraham and Sara. In Genesis 20:12, Abraham explains to Abimelech that “she actually is my sister, the daughter of my father but not the daughter of my mother, and she became my wife.”
A more subtle, but striking, example along the same lines comes from the related rule in chapter 20:17.
This also prohibits a man from taking either his father’s daughter or his mother’s daughter – a step-sister from either side – and seeing her nakedness. In condemning this union, Leviticus 20 said that it is hesed. That’s a very unusual usage. The word normally is translated as “lovingkindness,” and only rarely does it have a negative connotation of any sort. Lexicons and commentaries say that here it has some connotation of “disgrace,” but why the word should be used is hard to see. Strikingly, nearly the first use of this word in the Bible is found in Genesis 20:13, where Abraham is again describing to Abimelech the plan to say that Sarai is his sister rather than his wife. This is the “kindness” that she was going to show to her husband. The word seems to be chosen to draw attention to the connection between the situation prohibited in Leviticus 20 and the situation of Abraham.
Another example is in Leviticus 18:15, where the man is prohibited from uncovering the nakedness of his daughter-in-law. The word for “daughter-in-law” is kallah , and it is used again in 20:12 . The word is first used in connection with Abraham and Sarah’s relation to their father Terah (Genesis 11:31 ), but other than that, it is used prior to Leviticus 18 only in Genesis 38 (vv. 11, 16, 24), the story of Tamar and Judah. Judah , of course, takes his daughter-in-law thinking that she is a prostitute. So Judah , like Abraham comes under condemnation from the Levitical laws. Leviticus 18:18 says that a woman is not to take a woman and her sister who will cause vexation and rivalry. But of course, this is what Jacob did when he married both Leah and then Rachel.
What are we to make of this? Some of these actions are already condemned in Genesis. Judah is not in the right when he takes his daughter-in-law. On the contrary, she is more righteous than he because he doesn’t provide her with a levirate husband and she takes things into her own hands to do it. It is not good for Judah to take his son’s wife. He’s not executed for it, but it’s clearly wrong, and condemned already in Genesis 2. There has to be a break with the family of origin for a marriage to be legitimate. The man who takes his son’s wife is taking someone from his own “household.” Jacob doesn’t have a good time of it with his two wives. It’s not exactly condemned, but it’s not pretty.
But what about brother-sister incest, between Abraham and Sarai? What can we say about that? At the first, of course, this would be the only option. Adam and Eve’s children would have to marry one another. But Abram and Sarai are not in that position. There is no need for them to do what Cain and Abel had to do, take sisters. But there might be a link with the original situation. Abram and Sarai appear on the scene in the aftermath of the scattering at Babel . They may be in a “first generation” situation. This may be a way of pointing to the Adamic character of Abram’s calling.
But I want to try to make sense of this from the Levitical law itself. The closely link is in 20:17 . Let’s look at that passage in a little more detail. It’s a pretty full verse, and has a fairly elaborate chiastic structure:
A. Man takes sister, father or mother’s daughter
B. he sees her nakedness, she sees his
C. HESED
B’. cut off in eyes of people
A’. uncovers sister’s nakedness, bears guilt
From this, we can see not only that the passage uses the word hesed in a very unusual way, but also that it gives unusual attention to the faculty of sight. This is the only place in these two chapters where the emphasis is on “seeing nakedness,” and the only other places that use this terminology are Genesis 9:23; Lamentations 1:8; Ezekiel 16:37. The latter two have to do with the exposure of daughter Zion to shame and disgrace, so that her lovers see her exposed nakedness. Here, brother and sister see each other’s nakedness, and their punishment is literally sight for sight, eye for eye, because they are “cut off in the eyes of the people.” The people are to judgment them as cut off from the Lord, to judge them so. Ultimately, of course, this goes back to Genesis 2-3. Adam and Eve were naked from their creation, but didn’t know it. They were naked and unashamed until their eyes were opened, and they saw (“knew”) that they were naked. Sight and nakedness has to do with shame, and with having their eyes opened so they could pass judgment on themselves. Adam and Eve were the first brother-sister marriage.
Abram tells Abimelech that Sarai did him a kindness in saying she was his sister. She showed her “loyalty” to Abram. The idea in Leviticus 20 may be of an extreme and false loyalty. Hirsch: “If . . . hesed elsewhere has the meaning of an unrestrained going beyond the dictates of duty, giving oneself up to another where one is not duty bound to do so, here it can also very well mean giving oneself up to another where forbidden by duty.”
At least we can say that Leviticus is instructing Israel to make a break, on the issue of br other-sister marriage, with the earlier tradition of the patriarchs. Exodus/Leviticus institutes a new configuration of society for Israel, and marks a transition from one sort of relgio-social organization to another. The prohibition of brother-sister marriage is one of the markers of that transition.
Why? That remains to be determined.