Are there any Rabbis who require a DNA test for every child born as a means of preventing infidelity?

Question

If your wife commits infidelity, you are required to divorce her. This is taken from Mishneh Torah, Divorce 11.

וּבִכְלַל לָאו זֶה שֶׁכָּל אִשָּׁה שֶׁזִּנְּתָה תַּחַת בַּעְלָהּ נֶאֶסְרָה עָלָיו וְלוֹקֶה עָלֶיהָ שֶׁנֶּאֱמַר (דברים כד ד) ״‎אַחֲרֵי אֲשֶׁר הֻטַּמָּאָה״‎ וַהֲרֵי נִטְמְלאָה. אֶלָּא אִם כֵּן הָיְתָה אֵשֶׁת יִשְׂרָאֵל שֶׁנֶּאֶנְסָה. לְפִיכָךְ כָּל אִשָּׁה שֶׁנֶּאֶסְרָה עַל בַּעְלָהּ עַל יְדֵי קִנּוּי וּסְתִירָה אִם בָּעַל אוֹתָהּ מַכִּין אוֹתוֹ מַכַּת מַרְדּוּת. וְאִם עָבַר וְהֶחֱזִירָהּ אַחַר שֶׁגֵּרְשָׁהּ יוֹצִיא בְּגֵט:

Included in this prohibition is that every woman who engaged in adulterous relations becomes forbidden to her husband. He is punished by lashes [for engaging in marital relations with her],as [implied by the inclusion of the phrase] "after she has become tainted" in [Deuteronomy 24:4]: "And [an adulterous woman] has been tainted." There is one exception: the wife of an Israelite who was raped. Therefore, whenever a woman becomes forbidden to her husband, because she violated his warning against entering into privacy with another man, and he engages in relations with her, he is punished by stripes of rebellion. If after divorcing his wife [for such reasons], the husband transgresses and remarries her, he must divorce her.

My question is this.

Are there any Rabbis who require a DNA test for every child born as a means of preventing infidelity?

The logic of the practice:

1. It establishes honesty as everyone will always know their children are theirs and their spouses have been faithful to them.
2. It provides a strong preventative for infidelity since any woman who tries to hide the fact she has cheated on her husband and has become pregnant will be caught in the process.
3. If it did turn out the child wasn't that of the husband and the wife cheated, the husband would be required to leave her regardless and him staying in a relationship with her would be spiritually damaging to him since it would be considered a forbidden relationship.
4. The child of such a relationship would be considered a Mamzer and the community would need to know this as this child would be forbidden to marry within the common pool.

Because of this, I have to wonder if any Rabbi has ever considered enforcing a standard practice of DNA tests as a means of ensuring the stability of the community by weeding out those who might be unfaithful.

Has such a requirement ever been established by a Rabbi?

Answer 1

DNA testing is not required to determine the fidelity of a woman or the legitimacy of a child.

Firstly, a Jewish woman is not suspected of infidelity. A central principle in safekos [halachic doubt] is chazakah - and Jewish women have a chezkas kashrus. This is based on: (a) chezkas tzidkus (see Tosfos Chullin 11b), that we assume Jews don't transgress prohibitions until proven otherwise, and (b) chezkas heter l'baalah, which is a form of chazakah meikarah.

Regarding the legitimacy of the child, there is even more grounds to presume kashrus. Aside from the chezkas kashrus of the mother, there is also a rov - רוב בעילות הולכין אחר הבעל - that a child of a married woman was sired by her husband.

Even when faced with significant grounds of suspicion, we still assume the legitimacy of the child (Shulchan Aruch EH 4:15). According to many authorities (Chelkas Mechokek 4:14, Beis Shmuel 4:22), even if two witnesses testify to her being unfaithful, we still presume the child to be legitimate.

This rov is extremely powerful. Nodeh Beyehuda (EH I, 69) ruled that the child of a woman who became pregnant although her husband was previously childless and dangerously ill was legitimate, due to this rov. [See Lehoros Nassan (Vol 2, Siman 89) who ruled on a paternity case where the husband was considered medically infertile.]

Additionally, DNA paternity testing may not be halachically accepted to determine mamzerus. Besides for a skepticism to rely solely on newly discovered technology [grounds for skepticism in the scientific method is beyond the scope of this answer], even poskim who would rely on DNA testing in some areas of halacha (eg agunos) posit that they would not determine mamzerus with DNA testing. Also noteworthy, with the advancement of IVF and other fertility treatments, even a reliably negative paternity test would not be evidence of mamzerus.