This is a very complex question that would best be discussed with your rabbi on a case by case basis. Rabbi and lawyer Mark Popovsky wrote a tshuvah for the Conservative Movement’s Committee for Jewish Law and Standards that discusses these issues, entitled “Choosing Our Children’s Genes: The Use of Preimplantation Genetic Diagnosis.” (http://www.rabbinicalassembly.org/sites/default/files/public/halakhah/teshuvot/20052010/Popovsky_FINAL_preimplantation.pdf)
Within it, he discusses a range of issues, including the questions at hand. His conclusions include:
“A couple at an increased genetic risk of bearing a child with a genetic or chromosomal disorder
may employ PGD when all the following criteria are met:
a) the child will very likely manifest the disease should it be carried to term
b) the disease is fatal or associated with a severely debilitating condition
c) the disease has no effective therapies at present. “
and on our subject:
“PGD for other purposes such as to select the sex of a child or to choose other traits is not
permitted. “ (Ibid.)
The simple answer is that the Jewish perspective on genetic sex selection of children is a violation of halacha and morally unacceptable. The National Institute of Health has a paper discussing two very specific cases where Orthodox rabbis did allow for sex selection (both in cases where a sperm donor was required). (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3455094/). As a Conservative Rabbi, neither of those cases would allow for permission in my view, yet that is because I have a difference of opinion with the cited rabbis and couples on their need for sex selection in the first place!
No latitude given to select against terminal genetic diseases would allow for selecting properties such as intelligence or height.
As I opened, this is a complex issue and deserves specific attention to a specific case. There are other values at play that would allow for broader permission knowing the circumstances of the questioner. For example, Rabbi Avram Israel Reisner of the CJLS offered an “ideological dissent” from Rabbi Popovsky’s paper, arguing that more considerations should be allowed and would allow for a broader allowability of disease avoidance and trait selection.
Few questions are more pressing than those surrounding the world of genetic choice and modification. By definition it was a world the rabbis who wrote the Talmud and classic responsa knew nothing about and therefore current Jewish perspectives about it are still in formation. The authors of the CCAR responsa 5768.3 write that ,
Judaism permits us to exercise our technological power over the natural environment, but it also asks us to place appropriate limits upon that power.
In other words, there are situations in which our growing knowledge of genetics can be applied aggressively but others where we should refrain from acting. In particular, where it is a therapeutic response to a disease we should consider employing it. But when the goals is one of enhancement (intelligence or height) or family preference (sex of a child) we should not use genetic options.
Continuing on with Response 5768.3, we read,
We should emphasize that this is not a firm “no” to any and every application of these technologies for ends that are not strictly speaking medical. We recognize that there may be non-medical applications for human genetic enhancement that, when we consider each case on the basis of its own merits, will strike us as legitimate and compelling. We speak here rather of general tendencies: when the aim of genetic enhancement is not to fulfill the mitzvah o pikuach nefesh (saving a life), the “causes for concern” that we have raised would correspondingly become more urgent and predominant in our thinking.
While Reform Judaism is open to modern innovations and their possibilities to increase the presence of kiddusha, of holiness, in our lives, there is good reason to be cautious in our embrace of genetic selection or modification when it moves beyond the realm of saving a human life or directly improving someone’s health. From a Reform Jewish perspective, selecting for any of gender, enhanced appearance or appeal, or greater intelligence, should give us pause.