Fact: According to Megillat Esther, Mordechai and Esther were first cousins.
Background: This is a widespread misconception, even found in the renowned midrashic compilation of Louis Ginzberg. For example, in Legends of the Jews Vol. IV, page 387 he writes: “This lively interest displayed by Mordechai in Esther’s physical and spiritual welfare is not wholly attributable to an uncle’s and guardian’s solicitude in behalf of an orphaned niece.”
Yet, the relationship between Mordechai and Esther is explicitly described twice in the book of Esther. In Esther 2:7 the characters of Mordechai and Esther are introduced, and Esther is described as Mordechai’s bat dodo  — his uncle’s daughter, i.e., Mordechai’s first cousin. In Esther 2:15, when Esther is called to the king’s palace, her lineage is given as: Esther, the daughter of Avichayil, Mordechai’s uncle, i.e., she was Mordechai’s first cousin. The Targum Sheni elaborates further by specifying that it was Mordechai’s father and Esther’s father who were brothers.
There is an additional relationship found in the midrash. Rashi (on Esther 2:7) cites the Talmudic (Megillah 13a) exegesis that Mordechai not only raised, but later married, Esther. The Talmud (Megillah 13b) further derives from Esther 2:20 that they actually lived as husband and wife even subsequent to Esther’s being taken to the royal residence, up until the time she voluntarily went to Achashverosh. However, these rabbinic interpretations supplement the straightforward meaning of the text, and do not contradict it. In contrast, I have been unable to find any traditional source that says that Mordechai was Esther’s uncle, for to say so would contradict the text.
A possible source for this common misconception may be that two old, non-Jewish, translations, the Old Latin (3rd-5th century) and the Vulgate (ca 390-405 CE) actually have the uncle-niece relationship. In the Vulgate, verse 2:7 states that Mordechai raised the daughter of his brother, and in 2:15 it identifies Esther as the daughter of Avichayil, the brother of Mordechai!
This error may have crept into these translations because the even older Greek Septuagint uses the phrase “father’s brother” instead of a single word “uncle” as used in the Hebrew. If this was then the source text used for the Vulgate, it is possible that the translators accidentally left off the word “father’s” and ended up with Esther being Mordechai’s niece — daughter of his brother. The Catholic tradition was then based on the faulty Vulgate, and it is possible that the common Jewish misperception was influenced by that belief.
An alternate, simpler source is also possible. It may be that because Mordechai adopted and raised Esther as his daughter, he is perceived as having been much older. Hence the uncle-niece rather than the first cousin relationship comes to mind. In addition, the phrase “dod Mordechai,” used to describe Avichayil, Esther’s father, could actually trigger the association of the way one would call their “uncle Mordechai” as “dod Mordechai,” a nickname Queen Esther would technically not have used for her cousin Mordechai!
1. I would like to thank Michael Segal for assistance with researching this topic.
2. In IV: 384, Ginzberg wrote: “In Hebrew it means ‘she who conceals,’ a fitting name for the niece of Mordechai...She herself had been kept concealed for years in the house of her uncle....” In IV: 388 he wrote, “At the advice of her uncle, Esther....” There are no supporting footnotes for the relationship given.
3. A scriptural proof that “dod” is father’s brother can be found from Leviticus 18:14.
4. This exegesis is already found in the Septuagint (Esther 2:7) which reads: “When her parents were dead, he [Mordechai] brought her up as a wife for himself ...” Some modern commentators suggest that the Greek translator may have misread “bayit” instead of “bat,” a difference of a small yud. It is more likely he was familiar with the already well-known oral tradition that was later recorded in the Talmud.
5. They were originally permitted to remain together because a woman, other than the wife of a Kohain, who is forced to have relations with another man remains permitted to her husband (Ketubot 51b; Shulchan Aruch, EH 6:10-11). Esther’s living with Achashverosh was considered to be under duress (see Tosafot Ketubot 51b s.v. asurah . See also Tosafot Megillah 13b s.v. v’tovelet, about what Esther did to avoid ambiguous paternity). The Talmud (Megillah 15a, based on Esther 4:16) explains that from that fateful day when she voluntarily offered herself to Achashverosh as part of her plan to save the Jews, she was no longer permitted to return to Mordechai, and that was a personal sacrifice she made for her people.
6. See for example The Catholic Encyclopedia(5:556) that gives the relationship as “uncle (or cousin).”
Reprinted from JEWISH ACTION Magazine, Summer 5761/2001 issue