Feb 2012

Selecting the Traits of Children Prior to Birth

Timothy F. Murphy, PhD
Virtual Mentor. 2012;14(2):158-161. doi: 10.1001/virtualmentor.2012.14.2.oped1-1202.


Early in 2011, the Food and Drug Administration (FDA) directed a Virginia fertility clinic to stop offering MicroSort to people wanting to use it to select boys or girls in order to balance the children in their families. MicroSort is a sperm-sorting technology that stratifies X-bearing and Y-bearing gametes, allowing clinicians to offer a degree of control over the sex of a child. The FDA licenses this technology for use by parents who wish to avoid sex-linked genetic disorders in their children, so it is safe and effective. However, the FDA said that the fertility clinic could not offer it to parents who want to blend their families in a particular way because that would serve “no public health benefit” [1].

The law in the United States does not require practitioners to provide preconception methods of sex selection for reasons unrelated to the medical welfare of the child, which throws up another obstacle for parents wanting to select boys or girls. Professional organizations and public opinion are, however, making inroads in favor of the right to select the sex of children under some circumstances. In 2001, the Ethics Committee of the American Society of Reproductive Medicine advised that if sperm-sorting technologies could be demonstrated as safe and effective, clinicians should be able to offer them for parents wishing to blend their families by sex [2]. Not only that, but that same ethics committee held the door open to sex selection for other reasons, saying that if the social, psychological, and demographic effects of sex selection fall within an acceptable range, “then other nonmedical uses of gender selection might be considered.” On this interpretation, parents might choose, for example, to have only boys or only girls, or boys and girls in a particular order.

By contrast, some commentators object to sex selection for any reason. In the early 1980s, philosopher Michael Bayles argued that “a preference for one sex over the other, for its own sake, is simply sexism: It implies that one sex is intrinsically more valuable than another” and this preference is “irrational” [3]. This preference is sexist, Bayles believed, because parents’ expectations for their children can be met no matter their sex; both boys and girls can find their way to meaningful relationships and lives. This preference is irrational, Bayles believed, it is based on an unfounded belief, and he thinks that most preferences regarding the sex of children are just that. Suppose parents had two boys and wanted to have a girl. Bayles sees no rational basis for that preference, since he sees nothing inherently valuable in having two boys and one girl rather than any other combination. By his interpretation, trying to have children of a particular sex necessarily involves unfounded beliefs about the comparative value of boys and girls, birth order, and the overall number of boys and girls in a family.

Bayles doesn’t think any important good is achieved for parents or families by letting parents choose the sex of their children. On his account, children of any sex and in any birth order are good enough for what people need in families and relationships. Yet this come-what-may approach is too restrictive as a matter of moral argument. Some parents may have no sexist motives in wanting both boys and girls in a family, and there may be no sexist effects from blending families in a particular way. It is perhaps for these reasons that not even Bayles argues for the legal prohibition of sex selection. He says the harms involved don’t rise to a level that justifies state remedy.

Against this background, we can also ask whether arguments about sex selection stand in for selecting other traits in children through prenatal interventions. Some commentators have argued that not only is the selection of certain traits in children morally permissible, it is morally obligatory if the choice is within the parents’ power and the traits in question will confer advantages on the children [4]. Taking this position to a logical extreme, one commentator has argued that parents are morally required to choose girls over the boys, always, if they have the power to make that choice. This position is based on the theory that women have better lives than men because they live longer generally and can have experiences men cannot, such as childbearing [5].

We don’t have to actually make that choice, however, because all arguments about choosing the traits that will give children the best possible lives run into the trouble of establishing which possible life is better than the others. Even faced with that problem, it remains hard to argue that parents should not be entitled to confer benefits on their children through prenatal interventions, in much the same way they will do so after their birth.

In general, most discussion about using prenatal interventions to choose traits of children involves selecting traits that will contribute to intelligence, athleticism or strength, resistance to disease, and longevity. If the choice were available to us here and now, I think most people would be hard pressed to say that they would not want a bit more intelligence for themselves, longer endurance in exercise and sports, genetic immunity to certain viral infections, and the prospect of a longer life. If those outcomes are desirable for us here and now, how would those be any less desirable for children? How would it be immoral to work toward those outcomes for children just because the interventions took place before birth?

Some commentators worry that selecting the traits of children ‘commodifies’ them and turns them into commercial products. On this view, children are desired and loved only so far as they conform to their parents’ expectations. It is hard, however, to give this argument much credence since—after birth—parents go to extraordinary lengths to shape children in terms of their language, social skills, the relationships they have, as well as their political and religious views. How is it possible to accept that degree of influence over a child but reject the use of prenatal interventions that could confer benefits similar in kind and equal in importance?

As things stand, it is mostly genetic natural lottery that gives children the traits they have, but we have to ask why that status quo should prevail as the standard by which parents must abide as safe and effective interventions come along capable of conferring benefits on children. In other words, why are parents obliged to have children only as chance dictates? Some commentators have argued that intervening against chance usurps the choices ahead for children, by entraining them into futures of their parents’ design [6]. This argument is not persuasive either: a human being has enough choices ahead of him or her to render that worry irrelevant. All human beings face enough choices and circumstances to be able to author a meaningful life, regardless of what their parents originally intended, and that outcome would persist even if parents selected some traits prior to birth.

In 2010, Dutch researchers reported that women who rely on low-sodium, high-calcium diets and who have intercourse in a particular window of time following ovulation can increase their odds of having a girl [7]. The method is not foolproof, but what if it worked routinely? What if a comparable diet to increase the odds of having a boy were found? It would be hard to make the case that the method involved here, eating particular kinds of food, was objectionable in itself. It would be hard to make the case either that the motives of parents for wanting boys or girls are always objectionable. Unless there were some wild swing in the sex ratio caused by eating one’s way to children of the preferred sex, it would also be hard to make the case that this option would be objectionable in its effects either.

Human beings take steps all the time to order events in nature in ways that protect and enrich their lives. If the motives for selecting traits in children through prenatal interventions are not objectionable in themselves, if the interventions are safe and effective, and if no social harm comes from their use, it is possible to defend the selection of traits in children and maybe even, sometimes, call it an obligation.


  1. Dahl E. FDA bans gender selection procedure. Institute for Ethics and Emerging Technologies. May 17, 2011. Accessed December 10, 2011.

  2. Ethics Committee of the American Society of Reproductive Medicine. Preconception gender selection for nonmedical reasons. Fertil Steril. 2001;75(5):861-864.
  3. Bayles MD. Reproductive Ethics. Englewood Cliffs, NJ: Prentice-Hall; 1984: 35.

  4. Savulescu J. Procreative beneficence: why we should select the best possible children. Bioethics. 2001;15414-426.
  5. Sparrow R. Should human beings have sex? Sexual dimorphism and human enhancement. Am J Bioeth. 2010;10(7):3-12.
  6. Habermas J. The Future of Human Nature. Cambridge: Polity Press; 2003.

  7. Noorlander AM, Geraedts JPJ, Melissen JB. Female gender pre-selection by maternal diet in combination with timing of sexual intercourse – a prospective study. Reprod Biomed Online. 2010;21(6):794-802.


Virtual Mentor. 2012;14(2):158-161.



The viewpoints expressed in this article are those of the author(s) and do not necessarily reflect the views and policies of the AMA.