This is an obvious CYLOR question, but I am interested in whatever halachic information is available out there.

Suppose a couple got married without ever getting genetically tested for Tay-Sachs. When they decide to have a child, they are both tested and both turn out to be carriers. Does the mitzvah of having children still apply to them?

Also, is it acceptable for two people who know that they are carriers to get married in the first place?

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    For such a couple I would recommend en.wikipedia.org/wiki/Preimplantation_genetic_diagnosis if they could afford it. Note: I don't know what halacha says about this procedure. Obviously it includes IVF, and I don't believe there is any halachic issue with the genetric testing, but I don't know.
    – Ariel
    Aug 9, 2012 at 8:29
  • This looks like two separate questions. Oct 25, 2017 at 14:38

3 Answers 3


The first section in Nishmas Avraham on Even Haezer reads (in my own translation):

Rabbi S.Z. Auerbach zatzal wrote me:

I'm uncertain about someone with an hereditary disease whose descendants will be in pain all their days, or who suffers a blood-clotting disorder that passes to sons (hemophilia), whether he may therefore refrain from fulfilling the command to multiply, and can l'chat'chila marry a woman who is unable to give birth. After all, one need not spend more than a third or fifth of his assets even on a command that he could only fulfill now, and this man feels that the pain he and his children will have is worth much more than a third of his assets; but maybe it is not his place to investigate ways and means, and here, too [as by Chizkiya], we say "what are you getting into God's ways for? What God wants, do". I saw quoted from Igros Moshe that it's very obvious to him that one's obligated in fulfilling the command [to multiply], but to my mind it requires further investigation.

Later, in chapter 2, note א‎(3), Nishmas Avraham has:

Now I saw a responsum from Rabbi M. Feinstein zatzal, who writes:

About a man of twenty-five with Marfan syndrome, badly enough that he's needed heart surgery and is blind in one eye, and, if he marries and has children, his children, as far as we can tell now, have a 50% chance of having the same disease, as to whether it's forbidden for him to marry a woman who can give birth, or, to the contrary, whether he must marry such a woman in order to fulfill the command to multiply — it is obvious to my mind that if he's able to land a woman who knows he has this disease (for of course he must tell her before the wedding…) he may and indeed must marry her in order to satisfy the command to multiply. After all, there is a possibility he will have children who are healthy and sound; it is appropriate that he should hope and pray to God for such children.…

Rabbi Y. Zilberstein writes:

An engaged couple both of whom have defective chromosomes so that there's a chance they will have defective children — one should advise them not to marry one another. If they did, one should advise them to divorce. If divorce is difficult for them and they have not yet fulfilled the command to multiply, it makes sense that they are responsible for fulfilling it and should not consider the travails it will cause the offspring and themselves; about things like this is said "yours not to deal with the secrets of creation: do what you're commanded", and God will do what he deems best.…

Note that two carriers of an autosomal recessive disease like Tay-Sachs have but a 25% chance of each of their children's having the disease, less than the 50% discussed by Rav Moshe (but that the 50% applies to a Marfan sufferer no matter whom he marries (except another Marfan sufferer)). I imagine Rabbi Zilberstein was discussing a case like that of Tay-Sachs.

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    Afraid I'll have to strongly disagree. The cases discussed were where the child is likely to live into at least their 20s or 30s, but with medical problems. Tay-Sachs is a far worse prognosis.
    – Shalom
    Aug 9, 2012 at 10:17
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    Furthermore: Marfan means "if this guy gets married to anyone, 50% chance of problem." A Tay Sachs carrier can reduce their chance to 0 simply by finding a non-carrier. It's a false choice!
    – Shalom
    Aug 9, 2012 at 10:29
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    @Shalom, re your second comment (find a non-carrier), see the quote from Rabbi Zilberstein. Re dying young vs. not, I agree that that seems to be a difference, but, again, I suspect that that's included in Rabbi Zilberstein's statement: he doesn't seem to distinguish between those whose affected children are expected to die young and others.
    – msh210
    Aug 9, 2012 at 15:45
  • @Shalom Suffering aside, is a short life really worth less than no life at all? Seems quantitatively counterintuitive.
    – Loewian
    Oct 25, 2017 at 17:55
  • @Loewian that gets us to the false-choice point. If someone knows his offspring won't survive their first decade no matter what, we can discuss it. But a Tay Sachs carrier can find a non-carrier and have children who will live to a hundred.
    – Shalom
    Oct 25, 2017 at 18:27

When I went for genetic testing, the secular geneticist told me that her rule of thumb was "oh they'll just test each pregnancy and terminate the Tay-Sachs ones." Suffice to say that Rabbi Moshe Feinstein vehemently opposed that logic. His student Rabbi Tendler is therefore opposed to amniocentesis as the couple will then be pressured to terminate -- when according to Rabbi Feinstein it's not permitted to do so. (Note that other rabbis are more lenient in some unfortunate cases.)

I think the majority of Orthodox poskim today will tell you that two carriers really should look for other people to marry. It's the least-bad option. Hence the importance of checking for compatibility well before a relationship gets underway. (Rabbi Feinstein himself recommended finding one's carrier status as soon as one decides that s/he is "seriously of dating age", while the tests could be done earlier he didn't want more anxiety weighing on people. Today Dor Yeshorim removes the stigma by no one knowing their actual status.)

Should a couple realize they're both carriers: Rabbi Feinstein had ruled "if a man has a condition such that, regardless of who he marries, there's a 50% chance that his child will have medical problems but a life expectancy of several decades with treatment ... he should have faith and get married", with others questioning this. That's a far, far cry from saying that a couple who know there's a 25% chance any child they have won't survive preschool age should have "faith."!

In short:

  • A couple who know they're both carriers shouldn't get married.
  • If they're already married and determine they're carriers, it's reasonable to question whether the mitzva to try to conceive conventionally would apply -- as the emotional cost here is so high. I'd assume many would advise against it.
  • Adoption, or IVF with preimplantation testing, are both complex options that may be advisable, pending a couple's consultation with their rabbi.
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    Do you have citations for your quotations and paraphrases?
    – msh210
    Aug 9, 2012 at 15:46
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    @msh210, sorry I'm all over the place here. Igros Moshe on abortion; Rabbi Tendler article on amniocentesis; Igros Moshe on Marfan above; Igros Moshe on Tay-Sachs testing. I'd have to look them up.
    – Shalom
    Aug 9, 2012 at 22:55

According to most Poskim, one can fulfill the mitzva of procreation with a child born through IVF.

PGD (preimplantation genetic diagnosis) can be used in an IVF cycle to ensure that the child will not have Tay-Sachs (or another genetic disease).

I am familiar with several Orthodox couples who were advised by their Rabbis to take this route.

PGD is a relatively new technology. Many of the Rabbis quoted in other answers may have ruled differently had PGD been available.

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