By Horav Yosef Yeshaya Braun, member of the Badatz of Crown Heights
There are various reasons a person would undergo genetic testing. For those suffering from certain conditions—both children and adults—the presence of chromosomal mutations may reveal a diagnosis (or prognosis) for follow-up medical care.
Genetic testing can also prevent two carriers of certain medical conditions from marrying each other, thereby averting the heartbreak of bearing affected offspring. Contemporary poskim ask: are these tests halachically sanctioned?
These are the arguments against testing: In connection with the prohibited practice of consulting seers and psychics, the Torah says, “Tamim tihyeh im Hashem Elokecha” (Be complete [i.e., trusting] in Hashem, your G-d). Does this perhaps extend to all engagement with foretelling the future?
In addition, being too cautious may be halachically frowned upon, as the Chovos Halevavos (11th century philosophic work by Rabbi Bachya) cautions us, “Min hazehirus shelotarbeh lehizaher ([the obligation] to be cautious includes [the warning] not to be overly cautious). Another Torah principle can be extrapolated to forgo screening: since we follow the majority in all matters, perhaps we should ignore the possibility of a medical problem, since it is found only in a tiny percentage of the population (a lower frequency than the halachic conditions of miut hamatzui—see Halachah #578 for an overview of this phenomenon).
Additionally, some may argue: “Ein habrachah metzuyah ela b’davarhasamui min ha’ayin” (blessing is found only in those things that are hidden from the eye). The Gemara speaks of noteworthy people who would keep their illness a secret—so that Hashem’s deliverance may more readily come without the need for an open miracle.
Others note that perhaps we should be especially circumspect about pre-screening shidduchim. Matching zivugim (couples) is a matter of Hashem’s special intervention and we should not interfere by engaging in such pragmatic assessment.
Most poskim reject these arguments. Something that is considered proper medical procedure is supported by halachah as protecting our health. We need not fear violating “tamim tihyeh” when consulting with expert doctors whose professional background assure verifiable results (and not conjecture like fortune-tellers)—although there are those who remain cautious about publicizing negative results. Rabbi Moshe Feinstein (20th century halachic authority) states that straightforward medical testing is warranted; refusing a screening would be akin to entering a danger zone with eyes shut tight. It has become accepted in virtually all sectors of Klal Yisroel (the Jewish community) to utilize genetic screening.