In this week’s parshah Yaakov Avinu takes his entire family down to Mitzrayim. The Torah lists the family members who made this journey. On the list is Shimon’s son, Shaul. The pasuk refers to him as Shaul ben haCanaanis – the son of the Canaanis.
Rashi, quoting a medrash, explains that the Cannanis was actually Dinah, Shimon’s sister who was once together with a Cannani, Shechem. After Shimon and Levi destroyed the entire city of Shechem and rescued Dinah, she was worried that no one would want to marry her. She therefore made Shimon promise that he would marry her, which he did. Shaul was the son of Dinah and Shimon, and the pasuk refers to Dinah as a Cannanis because of her encounter with Shechem.
The Moshav Zekeinim LeBa’alei HaTosafos are bothered as to why Shimon was allowed to marry Dinah, since she was both his paternal and maternal sister. The Gemara in Sanhedrin 58a says that even a ben Noach is prohibited from marrying a maternal sister.
The Moshav Zekeinim LeBa’alei HaTosafos suggest that in fact Dinah was not Shimon’s maternal sister, only his paternal sister – who he was permitted to marry.
The well-known Gemara in Berachos 60a says that Yosef was conceived in Leah’s womb. Upon realizing that if Leah would give birth to another boy Rachel would not have the opportunity to bear the amount of boys that the maidservants had, Leah davened and miraculously switched her fetus to a girl, Dinah. The Targum Yonasan (30:21) takes this one step further by saying that while Yosef was already conceived in Leah’s womb, Dinah was conceived in Rachel’s womb. When Leah davened, the fetuses switched; Dinah was moved to Leah’s womb and Yosef to Rachel’s.
Based on this, Dina was conceived by Rachel. Therefore Shimon was permitted to marry her since a different mother conceived her.
Some Acharonim raised the following question: the Gemara in Megillah 13a explains the pasuk that says that Esther HaMalkah had no father or mother. She had no father as a result of his death before the time when he would be considered a father, namely when the fetus becomes recognizable (generally around the first trimester) The Gemara explains that she had no mother because her mother died when she was delivering Esther.
Rashi there explains that a man is called a father once the fetus is recognizable, while a woman is only called a mother when the baby is born. Based on this, why is the fact that Rachel’s conceiving of Dina enough for Rachel to be considered as Dina’s mother? We see that a woman is not considered a mother unless she gives birth to the child.
I would suggest that there is a difference between the Gemara in Megillah and the discussion of whose child we consider the baby to be. The Gemara in Megillah is explaining a pasuk that says that Esther did not have a father or mother. In order to reconcile the pasuk, the Gemara explains that Esther’s mother died when she was delivering her; thus she was not considered to have had a mother. However, we all know that she had a mother, as no human being is born without one. If we wanted to know who is considered to be the child’s mother regarding any other aspect, we would say it was the woman from whose womb she was conceived.
In other words, we can explain that as far as the mother is concerned she is not considered a mother until the baby is born. But regarding the child, its mother is determined by who conceived her. Esther indeed had a mother; it’s just that her mother was not considered a mother during her lifetime. Her mother was the woman from whose womb she was conceived.