When it comes to the complex and sensitive topic of using genetic engineering to produce offspring with specific characteristics, it is important to bear in mind that there are many medical techniques and methods referred to as “genetic engineering,” as well as varying reasons why one may choose to use them.

One common method of genetic engineering is to use PGD (Preimplantation Genetic Diagnosis), which involves screening pre-implanted fertilized eggs to ascertain whether they harbor specific mutations that may cause certain diseases such as Tay-Sachs or cystic fibrosis. After testing, only embryos found not to have these genetic mutations are then selected for implantation.

More recently developed methods include CRISPR-Cas9 gene editing, which allows genetic material to be added, removed or altered at particular locations in the genome. Although these methods can be used to eliminate various disease-causing mutations, they can also theoretically be used to select specific desired characteristics for the future baby.

As can be expected, this leads to all sorts of ethical, moral and halachic dilemmas.

Assisted Reproductive Technologies

Each method and procedure, including the many that weren’t mentioned here, has its own set of potential halachic issues.

Additionally, for the most part, all of the various methods of genetic engineering are dependent upon Assisted Reproductive Technology, such as IVF, which itself is fraught with potential halachic issues.

In the case of great need, certain procedures may be permitted with the guidance of an expert rabbi to ensure that all is done in a halachically acceptable manner.1

Assuming that the actual reproductive procedure is done according to halachah, we can now turn to the general question of genetic engineering.

Are Things Permissible by Default?

As is expected with new and emerging technologies, there is considerable debate regarding the permissibility of genetic engineering and, if it is permitted, what its parameters are.

The various issues raised on moral grounds include “playing G‑d” and it being a “slippery slope.” However, some halachic authorities2 point to a principle articulated by Rabbi Yisrael Lipschutz, author of the classic commentary to the Mishnah known as the Tiferet Yisrael, which states, “Any activity that we have no reason to prohibit is permitted in halachah without having to find a reason for its permissibility, for the Torah does not mention every permissible thing, but rather elaborates on only those things that are forbidden.”3 Thus, in the absence of any compelling reason to believe that many of these procedures and techniques are actually forbidden, we can assume that they are permitted.

Other authorities,4 however, counter that the Tiferet Yisrael doesn’t state that “whenever there is no prohibition mentioned, it is permitted”; rather, he states, “whenever we do not find reason for prohibition . . .” Thus, in a situation where even the average person may feel intuitively in his gut that certain aspects may be questionable, one cannot simply state that the “default” is that it is permissible before carefully examining the issues.5

Saving a Life

There is a difference between using genetic engineering in order to treat a hereditary disease and using it to change the characteristics of the child, such as height, complexion, intelligence, hair color, etc.

If it is being done simply to treat or prevent a hereditary illness, then most halachic authorities are in agreement that it would be permitted, as it is similar to other medical treatments. This is especially true when it comes to a potentially lifesaving treatment; after all, there is a halachic rule that pikuach nefesh (saving a life) overrides most prohibitions of the Torah.6

Partners with G‑d

What about using genetic engineering for non-medical things like height and hair color?

Some authorities postulate that although we do not have absolute autonomy in utilizing medical interventions (for example, euthanasia is prohibited even when the end is near), human beings serve as “partners with G‑d in the creation process.”7 Based on this, they are of the opinion that “if gene-editing technologies are used to change hair color with minimal or no health risks, then halachah would allow a person to use this technology for themselves. However, if minimal or serious health risks are associated with using this procedure, then halachah would prohibit gene-editing procedures to change their own hair color or enhance athleticism without a valid medical or psychological reason. Similarly, halachah would also prohibit non-medical applications of gene editing to their fertilized egg or child.”8

Others, however, are of the opinion that one shouldn’t use these techniques for non-medical purposes. Although G‑d explicitly granted mankind not only the ability but the responsibility to heal and prevent diseases, at a certain point making non-medical changes can be considered presumptuous, as if we know better than G‑d how to make a particular person.

In addition, at this stage we don’t necessarily know the ramifications of making these non-medical alterations.

Selecting a Gender

Regarding the question of using artificial procedures to choose the gender of a child, Rabbi Shlomo Zalman Auerbach,9 one of the leading halachic authorities of the 20th century, cites the following incident recorded in the Talmud:10

King Hezekiah was ill, and G‑d commanded the prophet Isaiah to go visit him. When he arrived, Isaiah proclaimed, “Thus said the L‑rd: Set your affairs in order, for you are going to die; you will not get well [lit. ‘you will die and not live’11].”

When Hezekiah inquired as to the reason for his punishment, Isaiah replied, “Because you did not marry and engage in procreation.”

King Hezekiah explained that he had foreseen with divine inspiration that unvirtuous children were destined to emerge from him. (Indeed, his future son was the evil King Menashe.)

To which the prophet retorted: “Why do you concern yourself with these hidden things of the Merciful One!? What you are commanded to do (i.e., the mitzvah of procreation) you must do, and that which G‑d wishes to do, He will do!”

Based on this, Rabbi Auerbach rules that one cannot use artificial procedures to choose the gender of the child (unless it were in the course of preventing some sort of disease). Seemingly, the same would be true regarding choosing other characteristics.

In Conclusion

There is considerable debate surrounding the permissibility of using genetic engineering in humans. Although most are of the opinion that it would be permissible for medical purposes, when it comes to using it for non-medical purposes, many are of the opinion that it should not be done.

Furthermore, even those who support gene editing are of the opinion that at least for the time being, until all the ramifications of gene editing on the macro and micro levels are known, these technologies should be used only for medical purposes, and not for non-medical enhancements.12