תנו רבנן שלשה שותפין יש באדם הקב"ה ואביו ואמו אביו מזריע הלובן שממנו עצמות וגידים וצפרנים ומוח שבראשו ולובן שבעין אמו מזרעת אודם שממנו עור ובשר ושערות ושחור שבעין והקב"ה נותן בו רוח ונשמה וקלסתר פנים וראיית העין ושמיעת האוזן ודבור פה והלוך רגלים ובינה והשכל
§ The Sages taught: There are three partners in the creation of a person: The Holy One, Blessed be He, and his father, and his mother. His father emits the white seed, from which the following body parts are formed: The bones, the sinews, the nails, the brain that is in its head, and the white of the eye. His mother emits red seed, from which are formed the skin, the flesh, the hair, and the black of the eye. And the Holy One, Blessed be He, inserts into him a spirit, a soul, his countenance [ukelaster], eyesight, hearing of the ear, the capability of speech of the mouth, the capability of walking with the legs, understanding, and wisdom.
״וְאַחַר יָלְדָה בַּת וַתִּקְרָא אֶת שְׁמָהּ דִּינָה״: מַאי ״וְאַחַר״? אָמַר רַב: לְאַחַר שֶׁדָּנָה לֵאָה דִּין בְּעַצְמָהּ וְאָמְרָה: שְׁנֵים עָשָׂר שְׁבָטִים עֲתִידִין לָצֵאת מִיַּעֲקֹב, שִׁשָּׁה יָצְאוּ מִמֶּנִּי וְאַרְבָּעָה מִן הַשְּׁפָחוֹת, הֲרֵי עֲשָׂרָה. אִם זֶה זָכָר, לֹא תְּהֵא אֲחוֹתִי רָחֵל כְּאַחַת הַשְּׁפָחוֹת, מִיָּד נֶהֶפְכָה לְבַת, שֶׁנֶּאֱמַר: ״וַתִּקְרָא אֶת שְׁמָהּ דִּינָה״. אֵין מַזְכִּירִין מַעֲשֵׂה נִסִּים.
“And afterwards she bore a daughter, and called her name Dina” (Genesis 30:21). The Gemara asks: What is meant by the addition of the word: Afterwards? What does the verse seek to convey by emphasizing that after the birth of Zebulun she gave birth to Dina? Rav said: After Leah passed judgment on herself and said: Twelve tribes are destined to descend from Jacob, six came from me and four from the maidservants, that is ten, and if this fetus is male, my sister Rachel will not even be the equivalent of one the maidservants; immediately the fetus was transformed into a daughter, as it is stated: And she called her name Dina; meaning she named her after her judgment [din]. The Gemara rejects this: One does not mention miraculous acts to teach general halakha.
בן הכנענית (Listing the sons of Simeon, Bereshit 46:10 lists 'Saul the son of the Canaanitish Woman' — means the son of Dinah, who had been associated with a Canaanite (Shechem). When they (her brothers) had killed Shechem, Dinah refused to leave the city until Simeon swore to her that he would marry her and regard the child she was about to bear as his own (cf. Genesis Rabbah 80:11).
וְגֵר שֶׁנִּתְגַּיֵּיר כְּקָטָן שֶׁנּוֹלַד דָּמֵי
And the legal status of a convert who just converted is like that of a child just born, and all previous family ties become irrelevant.
דְּאָמַר רָבָא גּוֹיָה מְעוּבֶּרֶת שֶׁנִּתְגַּיְּירָה בְּנָהּ אֵין צָרִיךְ טְבִילָה אַמַּאי אֵין צָרִיךְ טְבִילָה וְכִי תֵּימָא מִשּׁוּם דְּרַבִּי יִצְחָק דְּאָמַר רַבִּי יִצְחָק דְּבַר תּוֹרָה רוּבּוֹ וּמַקְפִּיד עָלָיו חוֹצֵץ רוּבּוֹ שֶׁאֵינוֹ מַקְפִּיד עָלָיו אֵינוֹ חוֹצֵץ וְהָא אָמַר רַב כָּהֲנָא לֹא שָׁנוּ אֶלָּא רוּבּוֹ אֲבָל כּוּלּוֹ חוֹצֵץ שָׁאנֵי עוּבָּר דְּהַיְינוּ רְבִיתֵיהּ
Rava said: If a pregnant gentile woman converted, then her son, who was a fetus at the time of the conversion, does not require immersion after he is born. But if the child is not assigned to its mother, why should he not require immersion? And if you would say that this is because of a statement of Rabbi Yitzḥak, there is still a difficulty. As Rabbi Yitzḥak said: By Torah law, if some substance is found on a person’s body during immersion, and it covers the majority of his body, and he is particular and wants the substance removed, only then is it considered an interposition that invalidates immersion in a ritual bath. If, however, the substance covers the majority of his body, but he is not particular about that substance, it is not considered an interposition. Accordingly, it may be argued that although the fetus is covered by its mother, since it is not particular about this necessary covering, the fetus itself is regarded as having undergone valid immersion. However, this is difficult, as didn’t Rav Kahana say that they taught this halakha that if one is not particular about the substance it is not considered an interposition only when the substance covers just a majority of his body; but if it covers all of it, it is considered an interposition by Torah law, even if he is not particular about it. The Gemara answers: A fetus is different, as this is its natural manner of growth. Its mother’s womb cannot be considered an interposition, as it is the fetus’ natural place of development, and therefore the fetus itself is regarded as having undergone immersion.
The Gemara cites another proof. Come and hear: Two twin brothers who are converts, and similarly twin brothers who are freed slaves, do not perform ḥalitza for each other’s wives, and they do not perform levirate marriage with them (an area of Halacha relevant to paternal siblings), and if they engage in intercourse with them they are not liable to receive karet for engaging in intercourse with a brother’s wife (a prohibition for maternal siblings). If they were not conceived in sanctity and only their birth was in sanctity, they do not perform ḥalitza or levirate marriage, but they are liable for engaging in intercourse with a brother’s wife. If they were conceived and born in sanctity, they are like Jews from birth in all of their matters. In any event, the baraita is teaching that regular converts are not liable for engaging in intercourse with a brother’s wife. It can be inferred that while there is no liability by Torah law,
Gestational Surrogacy: Establishing Maternity in Jewish Law By Aderet Liss
Contradicting this view that the genetic mother is the legal mother, new scientific data has emerged regarding what exactly occurs when a woman carries a child in her womb. The concept of mother-fetal cell exchange has been introduced recently, demonstrating that there is a profound physical connection between the gestational mother and the child. The new data show that stem cells from both the fetus and the gestational mother are exchanged via the placenta. During pregnancy, these stem cells are implanted in tissues of the other individual and can have significant implications. Maternal cells implanted into the fetus may benefit the fetus by suppressing its immune system from negatively responding to maternal antigens. The child contains not only its own cells derived from its genetic mother and father but also cells from its gestational mother. In addition, epigenetic studies show that environmental factors, such as the hormonal environment of the surrogate, her dietary habits, and her lifestyle, can influence different characteristics of the fetus. The gestational mother can essentially impact the personality and health of the fetus. These recent findings indicate that the surrogate does not simply serve as an incubator. Rather, biological bonds are created between the fetus and gestational mother.