Same question as here but for Judaism. I don't see how a married couple's becoming step-siblings is any different from step-siblings' become a married couple.

Suppose Alice and Bob are widows (or single adoptive parents or unmarried biological parents or whatever) and their respective children are Charlie and Dalia. Supposed all 4 are not married (or were never married or whatever, depends if widow or not).

If Alice and Bob marry, then Charlie and Dalia cannot marry (I think...?). But if Charlie and Dalia marry, then can Alice and Bob marry afterwards?

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    I know someone who had it happen to them, and they are quite religious. The reason the children don't usually marry is only because it they grew up together and it does not look good. Reb Yehudah Hachasid prohibits it, but it is not a blanket issur. If they did not grow up together there should be no issue
    – Chatzkel
    Commented Jul 22, 2022 at 2:45
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    @Chatzkel so co-parents-in-law can marry because actually step-siblings can marry?
    – BCLC
    Commented Jul 22, 2022 at 9:06
  • Anecdotally I have heard of several such occasions from a previous generation... usually for older parents that could no longer provide for themselves. They would marry the respective in-laws to each other and that way the children could maintain one residence for the parents rather than two (no yihud issues when married). Commented Jul 22, 2022 at 14:44
  • @Deuteronomy Source please then post answer.
    – BCLC
    Commented Jul 22, 2022 at 15:34
  • @BCLC my source is anecdotal, i.e. cases I am familiar with through community/family (nor does it furnish textual grounds on which to prove/disprove that it is permitted). That is why I posted a comment rather than an answer. Commented Jul 22, 2022 at 18:30

2 Answers 2


Can co-parents-in-law marry?

Yes, they may marry. R. Ayal Sheraga in his work Ish Yehudi (p. 270) addresses this question:

כשבני הזוג נעשו חורגים בנישואי הוריהם: ודע שאם קדמו נישואי הבנים לנישואי ההורים ועל ידי נישואי ההורים כעת נעשו הבנים חורגים אין בזה כל חשש וכ"כ בספר שבעים תמרים שם והוכיח מלשון הצוואה דריה"ח אינו אומר רק שהורגין לא ישאו זה את זה שנקט בלשונו וכן האיש שהוא אלמן ולו בן ונשא אשה ולה בא' הרי שהאיש האלמן נשא מתחילה האלמנה ונמצא שהבן שלו והבת שלה חורגין אבל אם האיש נשא אשה ואחר הנישואין שלהם רוצים אבי האשה ואם האיש לישא זה את זו אין בזה חשש אף שנמצא כעת שהבן והבת שני חורגים אין בכך כלום כיון שכבר נישאו מקודם וע"ש שהורה למעשה באיש אלמן אחד שהשתדך לישא אלמנה ולו בן ולה בת אשר גם הם נתקשרו לישא זה את זו שיקדימו נישואי ' הבת והבן לנישואי עצמן ובזה ינצלו מחשש שלא ישאו חורגין זה את זה ע"ש וכ"כ בשו"ת פרי חיים אוה"ע מי' ה' והביאו במקור חסד שם וכ"כ במילי דהמידותא שם שאם היה חשש בכך אינו רק על תחילת החתונה אבל כשאחר ההתונה נעשו חורגין אין השש עוד וע"י תנאים קודם החתונה ועי"ז נעשו חורגים ג"כ יש קולא ע"ש ומדבריו נראה שא"צ להקדים חתונת הבנים קודם אלא די שיקדימו התקשרות התנאים בלבד.

To paraphrase: there is absolutely no prohibition in two in laws to marry each other. Even where one accounts for the Testament of R. Yehudah ha-Hasid, which prohibits step-siblings from marrying each other, that would only be the case where the parents are married first, however where the children marry first, there isn't anything to be concerned or suspect about. Furthermore, it is sufficient that the children simply have the Tannaim performed, and they needn't be technically fully married before the parents marriage.

  • AHA so in Judaism it depends on who is 1st between the children and the parents? ... Wait a minute so you disagree with N.T.? This looks the opposite of what you said in comment 'though I agree, your answer would be greatly improved if it were to provide sources backing up your assertions.'
    – BCLC
    Commented Nov 14, 2022 at 8:05
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    @BCLC there's no contradiction. If one wanted supererogatorily adhere to the concern of R. Yehudah ha-Hasid, then one would be careful to have the children perform Tannaim first, before proceeding with the parents' marriage. However m'ikkar ha-din (according to the letter of the law), this is not required. So yes, I agree with N.T. and appreciate the anecdotal evidence, but generally prefer textual evidence in answers. Commented Dec 7, 2022 at 19:06

There is no rule that step-siblings cannot marry. In fact, the Chofetz Chaim of blessed memory married his step-sister. Step-parents can also marry. A friend of mine had his grandfather and grandmother marry after their spouses had died.

  • though I agree, your answer would be greatly improved if it were to provide sources backing up your assertions. Commented Jul 24, 2022 at 23:01
  • I thought you couldn’t marry a step sister? Or is that only your step mom? Commented Jul 24, 2022 at 23:04
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    Stepmom is forbidden because she is your father's wife. Halachically you are not related to your stepsister, so no problem. @Deuteronomy I don't know where to find sources that something is not forbidden, but the Chafetz Chaim did it, so it can't be forbidden.
    – N.T.
    Commented Jul 25, 2022 at 0:43
  • @N.T. "I don't know where to find sources that something is not forbidden" See Meqor Hesed on no. 29 of the last testament of R. Yehudah ha-Hasid. See also R. Yaaqov Moshkovitz's Batim Lebhadim p. 312 fn. no. 76. where the issue of stepsibling marriage is addressed. Cf. Ish Yehudi p. 270. Commented Jul 25, 2022 at 13:49

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