Should Pro-Choice and Pro-Life Approaches to Reproductive Rights Carry an "Incest Exception"?

My last column analyzed the views of people who would ban abortion generally but allow an exception for pregnancies resulting from rape. In response, I received an email from a reader, Bruce Moldovan, who wondered why any pro-life person would support an incest exception (as John McCain, for example, has). This raises the more general issue of why both the right and the left take a distinctive approach to incest. In this column, I will consider that question.

Incest within a Reproductive Rights Framework

The notion that "incest" ought to be treated as distinctive, in the context of reproductive rights, is not unique to pro-life compromise on the issue of abortion.

To give one example, Alexander Sanger, grandson of Margaret Sanger (the founder of the organization that eventually became Planned Parenthood), argues in his book, Beyond Choice, that we ought to view ready access to and use of contraception and abortion as successful human strategies for survival - strategies that we, as a species, prohibit at our peril.

When a particular exercise of reproductive choice endangers human survival prospects, Sanger suggests, the rights of the individual should give way to the needs of the species. As two illustrations, he provides the ban on reproductive cloning (a technology which, he claims, would undermine the genetic diversity necessary for successful evolution in a changing world), and the criminal prohibition against incest (a practice that, he claims, would hurt humanity by increasing the prevalence of birth defects in the population).

In keeping with Sanger's perspective, liberals defending a right of privacy to select one's sexual partner typically emphasize the distinction between the practice of incest - for which, they hold, there should be no recognition - and other practices (including contraception, abortion, and gay and lesbian relations) - which, they hold, should be recognized and protected.

The notion that there ought to be an "incest exception" to bans on abortion, otherwise supported by some members of the pro-life community, is simply the flip-side of the liberal approach: However we view sexual and reproductive choice generally, incest exceptionalism counsels that we suspend that view when faced with the risk of incestuous reproduction.

Incest and Child Abuse

To question the virtually universal ban on incest is, at one level, to seem like a dunce or a deliberate provocateur. How can anyone support a right to incest? Isn't that tantamount to supporting child molestation? And isn't the nearly-universal taboo on incestuous relationships in place for a reason?

First, by "incest," let me be extremely clear that I do not mean sexual relations that involve a child. Such relations are rightly criminal, because children are too young to provide consent and therefore, they suffer abuse when an adult subjects their bodies to sexual contact. This is true regardless of whether the adult is a parent, an uncle, a stranger, or the neighborhood pedophile. We might understandably consider such abuse to be worse when the offender also occupies the role of parent or guardian, but that point is less about incest than it is about the betrayal of a trust. For that reason, most people would rightly view molestation by an adoptive parent as equally outrageous, though it is not genetically an incestuous relationship.

It poses no contradiction, then, to support sexual freedom generally while opposing incest involving a child: Like rape, child molestation is a violation that necessarily falls outside the heading of "two consenting adults." By the same token, a pro-life advocate who supports an exception for victims of child molestation faces no greater challenge in defending this position, than he would in defending the rape exception more generally. (For more on the challenges posed by defending the rape exception, see my prior column.)

One need not treat "incest" as special, in other words, to protect children from abuse (or from the consequences that follow from that abuse).

A Genetic Defense of the Species

To defend a ban on incest (or a special allowance for abortion in cases of incest), one must, however, confront the case of consensual incestuous sexual activity between adults. Consider, for example, a brother and sister who were separated at birth and raised in different homes. They meet as adults, begin dating, and fall in love. In undergoing simple blood tests, they learn that they are in fact biological siblings. They still want to marry, but the law prohibits them from doing so and, indeed, threatens to punish them criminally if they engage in sexual intercourse with each other.

Why do we have such a prohibition? It is to protect the species from the increased likelihood of birth defects. The genes for a birth defect are often recessive, which means that a child must inherit the gene from two parents in order to develop the harmful trait in question. Tay Sachs disease and Cystic Fibrosis are examples.

When two sexual partners are genetically related to each other, their relation - by definition - means that they share a large number of genes in common (depending, of course, on how closely related they are). Two siblings share, on average, 50% of their genetic endowment (not otherwise common to the entire species). It follows that whatever genetic trait is present in one of the partners is far more likely to find its defective analogue in a sibling than in a random member of the surrounding community.

The result? More birth defects in the children of siblings. Thus, if everyone must find a mate outside of the immediate family, there are likely to be fewer birth defects than if everyone is marrying his or her close relatives. And with fewer birth defects, there will be a heartier population, better able to survive and reproduce into the future.

A Natural Taboo

Apparently because of the selective evolutionary advantage of marrying outside the family, most of us have a natural aversion to the idea of sleeping with our relatives. There is, indeed, evidence that people are likely to be most sexually aroused by the odors of other people whose genes are most different from their own.

If we're built to avoid close couplings, then doesn't it seem sensible (and properly distinctive) to criminally prohibit incest, if one is a liberal, or to allow abortions of the products of incest, if one is pro-life? Not necessarily.

The fact that an overwhelming majority of the adult population finds revolting the very thought of intimacy with a parent or sibling - that such aversion seems hard-wired - suggests that, in fact, there is no real risk of large numbers of incestuous couplings. This, in turn, means that it is unnecessary to "make an example" of the rare pair of consenting adults who both lack the relevant aversion.

The Categorical Imperative

Immanuel Kant introduced the moral notion that one should behave in a manner that, if adopted as an axiom by the entire population, would not be destructive. Kant referred to the requirement of generalizing one's proposed course of action in this way as the "categorical imperative." As a Kantian, if I feel like stealing an iPod from Circuit City, I cannot rationalize it by noting the slight impact that such a theft would have. If everyone behaved as I did, the harmful impact would be grave and unjustifiable - and that is enough to make my iPod theft immoral.

If one takes a Kantian approach to incest, then it might seem that even though a particular incestuous coupling may have little impact on the population, the generalization of this practice could bring catastrophe to our species. Therefore, one might say, it is appropriate to punish incest criminally and thereby penalize those people who act in a manner that could not, without courting disaster, be generalized to everyone else.

The problem with this argument, however, even if one is a strict Kantian, is that the "harm" of incest - its tendency to increase the odds of birth defects - is not unique to incest and is also not universal in cases of incest. A ban on incest is, accordingly, both under- and over-inclusive.

Under- and Over-Inclusiveness

In a world in which genetic testing is unavailable, avoiding incest may be among the only steps one can take (short of infanticide) to guard against congenital birth defects. In our world, however, people can (and often do) undergo genetic testing before they decide to have a child together. People might undergo a test for a particular gene before marrying, before trying to achieve conception, or during an extant pregnancy.

As a result of this possibility, a true effort to minimize birth defects - even by force of the criminal law - would require genetic testing and would prohibit the union of individuals who share a gene for a particular disease or disorder, whether or not the man and woman were related. In this sense, then, the current ban is under-inclusive. Within some communities of Eastern European Jews, for example, where the incidence of the gene for Tay Sachs disease is heightened, people are strongly encouraged to be tested and to plan their marriages accordingly.

A broader version of such an approach could become the law, if we wanted to prioritize the prevention of genetic birth defects. Our reaction to such efforts, however, is to view them with suspicion and even outrage, because they are literally "eugenic" policies, reminiscent of what the Nazis (not to mention the U.S., in the late Nineteenth and early Twentieth Centuries) did. Though it would be bad for the species to have enormous numbers of people born with congenital birth defects, we rely on voluntary efforts (including optional genetic counseling for couples) and choose not to impose mandatory eugenics on the population. Given the relative infrequency of incestuous couplings, it would seem arbitrary to single them out for coercive regulation in the campaign against genetic birth defects.

Similarly, it would seem arbitrary for one who considers himself generally "pro-life" to make an exception, on this basis, only for pregnancies that are the result of incest. Indeed, many pro-lifers emphatically oppose permitting abortion even when amniocentesis reveals the near-certainty of genetic illness as bad as or worse than the illnesses that incest may risk.

Conversely, there are many incestuous couplings that will not lead to birth defects, even though the odds increase. Indeed, an incestuous couple might - in any given case - have genes that are, relative to a particular non-related couple, unlikely to lead to a birth defect. Furthermore, many couples who do not intend to have (or cannot have) children will not create a birth-defect problem in the population. In this sense, a ban on incest is over-inclusive. Sexual relationships are, despite religious efforts to the contrary, not synonymous with procreation, and a criminal law premised on the view that they are is necessarily going to be quite imprecise.

Encouraging Incest? No

Despite my foregoing defense of a legal right to incest, I do not believe that incest is a wonderful thing that ought to be encouraged. If it turned out that I was wrong and that millions of sibling couples were patiently waiting for legalization to attempt to populate the earth, I would find the prospect profoundly disturbing. But this is true, as well, of other choices that we allow individuals to make in a free country: For example, I would be disturbed to learn that everyone in the population had turned away from reproduction and would practice contraception for the rest of their lives. Such a course of events would, in fact, lead to human extinction far more quickly than even universal incest. Yet I suspect that neither of these nightmare scenarios is remotely likely to come to pass.

Survival of the species depends on a complicated combination of genetic and environmental factors, some of which may be counterintuitive and unknown to us. Rather than embrace a discriminatory brand of mandatory eugenics, we should focus our efforts on facilitating and informing voluntary choices.

Like the species as a whole, every individual within it has an inherent interest in protecting the health and survival of her family and can - and generally should - be relied on to act accordingly, without legal intervention.