Did Abraham Marry His Sister?

March 16, 2021 - Nisan 3, 5781

Did Abraham Marry His Sister?

In Genesis 20:12 Abraham tells Avimelech that Sarah is his sister. However, we see earlier in Genesis 11:29 that Sarah is Avraham's niece. Our tradition tells us that Iscah was actually Sarah (she had two names, a common occurrence in the Torah). If Iscah is Sarah, and Sarah is the daughter of Haran, and Haran is Abraham's brother, then Sarah is Abraham's niece, not his sister. Genesis 11:26 tells us that Abraham and Haran were brothers.

How Do We Know That Iscah is Sarah?

That Iscah is Sarah also makes sense because the name "Iscah" pops out of nowhere suddenly in 11:29; Sarah and Milcah appear as parallels as the respective wives of Abraham and Nahor, both of whom married the daughters of their brother, Haran. We therefore should have expected the text to read as follows:

And Abram and Nahor took themselves wives; the name of Abram's wife was Sarai, and the name of Nahor's wife was Milcah, the daughter of Haran, the father of Milcah and the father of Sarai.

Instead of "Sarah," the Torah uses the name "Iscah," indicating that Iscah was Sarah.

Why Did Abraham Refer to His Wife as His Sister?

If Sarah was Abraham's niece, why did he refer to her as his sister?

According to AskNoah.org, "Note that Abraham said this to appease Abimelech. It was actually only figuratively true in his case, since Sarah was the daughter of Abraham’s brother. They had the same paternal grandfather, whom people often referred to as “father”.

In other words, one is allowed to lie to save his life, and so Abraham was permitted to do so in this case. However, being a person of the moral and spiritual stature that Abraham was, lying was not an ideal course of action for him. When he therefore used the term "sister" in reference to Sarah, he used it in a way commonly used in the Tanakh and in Semitic cultures as a broader term referring to next of kin. 

When studying Torah we generally use earlier verses as the basis for later verses. The genealogies in Genesis 11:29 above precede the interaction with the Pharaoh in Genesis 20:12.

A Brother is Not Always A Brother

Nevertheless, Genesis 14:12 also contains a proof that the word "brother" does not always mean a literal brother. A few verses later Genesis 14:16 refers to Lot as Abraham's brother.

The Torah refers to Lot both as "the son of Abram's brother," i.e., his nephew, and as "his brother," i.e., his brother. It's possible to refer to a nephew as a brother, but not to a brother as a nephew. Therefore Lot was Abraham's nephew. We can therefore also understand that Sarah was not Abraham's sister even though the Torah uses the word "sister" to refer to her.

This also teaches us that Sarah and Lot were actually brother and sister.

We also see the broader context of the word "brother" in Deuteronomy 18:15-19. The context of this verse was God's appointment of Moses' successor and was addressed to the entire nation of Israel. By definition because the entire nation of Israel were not literally brothers, "from your brothers" means "from your kinsmen." The word "brother" or "sister" can double as literal siblings or as extended family, and is determined by context.