In 1999, a popular press magazine published the concerns of two scientists that many disorders go unrecognized as having an infectious origin. A paradigmatic example is the relatively recent discovery that many human stomach ulcers are caused by a bacterium rather than by diet, stress, or environmental causes. These scientists also believe that homosexuality may be caused by a microbial infection. They say that the severe fitness problem of homosexuality "is a red flag that should not be ignored, and that an infectious process should not be ignored, and that an infectious process should at least be explored."1 These scientists believe that if homosexuality were heritable, the responsible genes would disappear quickly — because same-sex interactions do not lead to children. These scientists think that this challenge to reproductive fitness could not be overcome by random new genetic mutations that could, theoretically, re-introduce genes for homosexuality back into the gene pool. They believe there is more homosexuality than could be accounted for by new mutations. They think it is, therefore, a mistake to study homosexuality as if it were a genetic trait.

Despite some degree of logical plausibility, there is ultimately very little to be said in favor of these contentions. In its focus on the reduced reproductive rates of homosexual men and women, the account ignores other mechanisms by which genetic traits endure across generations. More importantly, the account is offered without any evidence whatsoever about which microbe might work how to generate homosexual interests. A peer-reviewed science journal turned this account away, but it nevertheless found its way into the pages of the public press. I take this to mean that while science is interested in the rigorous study of homosexuality, the public does not always wait for the evidence to come in, which leads to the question "which comes first, a theory of homosexuality or the public’s willingness to believe it?"

The viral theory of homosexuality is plausible but it is not any more plausible than current genetic explanations. Moreover, the ease with which theories of homosexuality seep into public discourse raises important ethical questions about the way in which researchers ought to communicate their various theories to the public. Given that an unfounded theory of homosexuality can do more damage than good, researchers should raise the bar in regard to the views they propound about its origin.

Must Homosexuality be Non-genetic?

During the 1990s, the view that homosexuality was rooted in genetics gained a good measure of public acceptance. The Human Genome Project was proceeding apace, and nobody wanted to be left off the genetic map. Of course, a genetic approach to homosexuality is anything but novel. Many of the early Western sexologists were happy to treat homosexuality as a genetic degeneracy, as a kind of evolutionary dead end.2

The idea that homosexuality was rooted in an infectious microbe would, however, challenge these genetic approaches. A microbial source of homosexuality would invite comparisons with pathogenic infections. Before jettisoning a genetic paradigm, however, it must be shown that genetics cannot really account for the durability of homosexuality. It is far from clear that genetics lacks the explanatory power required to account for the endurance and incidence of homosexuality.

Sociobiological accounts go a long way toward making a genetic basis for homosexuality plausible in the sense that the reduced fitness of some individuals does not mean that their genetic endowment must necessarily disappear from the gene pool. Sociobiology proceeds by emphasizing the genetic fitness of kinship groups, small clusters of individuals, rather than individuals.3 On this view, the relevant unit for analysis is the group’s survival rather than individual genetic survival. Any genetic makeup that contributes to the survival of the kinship group is by definition adaptive. It is the hypothesis of sociobiology that homosexuality contributes to the survival of the kinship group by enabling contributions that are not possible otherwise. For example, if men and women who are strictly homosexual have fewer children of their own, they can be available for other tasks important to the survival of the group. They might help in the raising and rearing of children and perform other tasks suitable to the childless. If so, homosexuality would be an integral component in the distribution of labor necessary for survival. The kinship group that has genes for homosexuality distributed across its members would be the group more likely to survive. Thus would the genes be preserved even if individual homosexual men and women did not have children.

An alternate account of the genetic durability of homosexuality in spite of reduced offspring relies on the possibility that the gene confers some direct survival benefit to individuals when not fully expressed. Scientists have long noted, for example, that some people have a resistance to malaria when they carry a particular, unexpressed genetic allele even though two copies lead to sickle cell anemia. Though no one has offered any hard evidence that a gene for homosexuality confers any advantage in this way, it is plausible that carriers of the alleles for homosexuality might gain some survival advantage even if there was a reproductive disadvantage attached.

As these matters have been well considered elsewhere, I do not wish to discuss the evidence for and against them.4 It is enough to note that sociobiological accounts offer plausible accounts of the genetic durability of homosexuality and — if substantiated — could dispel the puzzlement about why homosexuality endures even if men and women who are strictly homosexual have fewer genetic offspring than others.

The View from Genetics

Another main source of the view of that homosexuality is genetic comes from a string of research reports. These include a neuroanatomical study which found a size differential in brain structures between homosexual and heterosexual men, a difference possibly related to the genetic origins of that particular part of the brain.5 Other reports noted the way in which patterns of sibling homosexuality followed genetic relatedness.6 Twin studies were of special interest in this regard. A capstone study in the genetics of male homosexuality found that a genetic region in homosexual males was much more often shared by homosexual siblings than by heterosexual siblings.7 The implication of this latter study was that there might be some genetic aspect of that region that disposed men toward homosexuality. The same researchers did not find this sort of correlation in women, and this finding has not been confirmed by other scientists.8 As it is, these studies in their totality suggest that a gene for homosexuality could be at work. Whether this is in fact true or not remains to be seen. The studies do invigorate genetics, though it has to be said that the hard evidence is still out that in a simple way genes cause homosexuality.9 Yet the correlations made in these studies and the prospect of matrilineal heredity do suggest a mechanism by which a genetic contribution to homosexuality might endure across generations.

It is also worth noting that the apparent childlessness of many homosexual men and women may be an artefact of the contemporary organization of culture into distinct gay and straight enclaves. While homosexuality is known in vast numbers of cultures across time, that sexuality has not usually been considered an either/or proposition. The extent to which contemporary Western culture divides gay and straight identities is largely without precedent in human culture. Historically, many women and men with same-sex interests did not confine themselves exclusively to same-sex relations, though certainly some did. Large numbers of men and women with same-sex interests functioned bisexually and had children. Homosexuality need not, therefore, always translate into childlessness, which is to say into genetic oblivion. That being the case, the genetic origins of homosexuality would remain unproblematic.

The considerations here hardly prove that sexual orientation is genetic in any definitive sense. The kind of science necessary to substantiate that contention has yet to be done, if it can be done at all. There is, after all, a school of thought that holds that just as any child can learn to speak any language, any child can come to have any set of sexual interests and that the influences that ultimately shape sexual interest are cultural rather than biological. Nonetheless, the considerations here do establish that homosexuality is compatible with a genetic origin. There is no trait of homosexuality that requires science to go looking outside genetics for the determinants of sexual orientation.

What if a Microbe Causes Homosexuality?

At present, the scientists who have raised the question of a microbial cause of homosexuality have identified no responsible microbe, no mechanism by which infection occurs, no pathway by which the infection works, no timetable during which infection occurs, and no estimate of the possibility of controlling that microbe through prevention or treatment. The burden of scientific proof has hardly been approached let alone met.

Nevertheless, if homosexuality has an infectious origin, it would remain to be seen whether it is communicable like air-borne infections, like sexually communicable diseases, or like perinatal infections passed from mother to child. One could even imagine that it has an environmental origin and could be picked up from an animal reservoir in the wild. Debate about the genetic study of homosexuality did not fail to raise worries that research could re-pathologize homosexuality and open the door to methods of prevention and treatment. These same issues would apply to the treatment of homosexuality as an infectious condition, and with a vengeance: if there is an infection at work one could try to prevent it or treat it. For example, if the infection in question worked to block a neurological function observed in heterosexual women and men, it could be tempting to some to see that effect as pathological. If an enzyme were missing because of the infection, it could be tempting to define that deficit as pathological. While we all happily house microbes by the millions, the presence of a microbial infection in homosexuals that went unparalleled in heterosexuals might be enough for some people to see the process entirely in terms of pathology. The matter would not, of course, be this simple.

On perfectly reasonable grounds, one could argue that the effect of the microbe is benign regardless of what it does physiologically because not all differences — even microbial ones — are pathological. If the outcome of the infection is not itself inherently objectionable, it is hard to see what case could be made that the infection is pathological. It would be entirely fair to hold that a homosexuality microbe can happily coexist with human life in the same way digestive tract microbes happily do the work essential to human life. There are, therefore, counter-arguments to the view that an infectious origin of homosexuality is necessarily pathological, but the effect of finding a microbe for homosexuality would as a matter of politics re-open the question of pathology all over again for those unwilling to cede the moral innocence of homosexuality. There are cultural forces ever ready to re-invigorate the view of homosexuality as pathological, and the discovery of a microbial cause would be grist for that mill. This time around, however, it would have to be infectious disease specialists on the front line of prevention and treatment, not psychiatrists.

Whatever might happen politically and culturally, if a microbial infection were at the root of homosexuality, there would have to be a new spin on a variety of questions that have already been asked in regard to the prevention and treatment of homosexuality. Would a treatment against the infection work at any age, or would it be effective only at a certain point in development? If the microbe could be treated, would insurance companies pick up the tab for those people who wanted to cure themselves of homosexuality? Could insurance companies refuse to offer coverage to homosexually-infected people on the grounds that they had a pre-existing condition or that infected males were at disproportionately higher risk of contracting an HIV infection? If a vaccine could thwart the microbe, would schools require incoming students to show evidence of immunization against the homosexual microbe? If a child were born with an infection, could parents sue physicians for failing to meet the standard of due diligence in protecting their newborn against prenatal infection? Could parents sue a pediatrician who failed to prevent infection/homosexuality in their adolescent? These kinds of questions could be easily multiplied.

Even larger questions would loom for the fate of lesbian and gay populations in general. What would life be like for lesbians and gay men if there were a treatment for the infection that causes most homosexuality? Would lesbians and gay men be accepted in their sexual identities if the culture at large thought homosexuality had more in common with bacterial meningitis than with religious or political identities? What would happen to efforts to secure the right to protection from invidious acts of discrimination against lesbians and gay men? Would anti-discrimination efforts dissipate, with the culture at large believing that – after all — there really are no lesbians or gay men in nature, only people whose recourse to protection from discrimination should be looked for in a physician’s office rather than in a court of law? Certainly those theorists who argue that discrimination against homosexuals should be treated by the heightened judicial standard of suspect classification would have to re-think the way they argue that homosexuality is immutable.10 Beyond that question, could the U.S. military reframe its objections to lesbian and gay personnel by arguing that homosexuality is incompatible with the state of health necessary to maintain an effective fighting force? Perhaps women and men would be tested for the presence of any active infection prior to induction in order to confirm that they would not be disposed toward the homosexual conduct that is grounds for exclusion from the military. How, moreover, would lesbians and gay men react to one another, especially those who believe they choose their sexuality for political reasons rather than for reasons of biology? Would some people be "more homosexual" than others? Surely these questions, and more, would follow in the wake a finding that homosexuality is the neurological effect of a microbial infection, which is to say that the effects of a microbial theory of homosexuality would be anything but idle.

Evidence and Ethics in Research

In the early years of the AIDS epidemic, three French researchers went before a news conference and recommended that people with AIDS seek treatment with an immune-suppressing drug. Never mind that they had themselves only treated three people this way. Never mind that one of those patients had in fact died before the press conference. Never mind that the recommendation proved to be utterly groundless. The physicians told the public that the urgency of their findings was too important to wait out the normal process of scientific review. They felt compelled to air their views in front of international television crews. Even if these physicians can be forgiven by some indulgence, it is unclear what urgency could attach to new theories of homosexuality that are aired first in the public press. There is no medical benefit or social policy at stake, and certainly no one’s life hangs in the balance. Far from clarifying things, this idea only throws the nature of homosexuality into further contention. Moreover, the very means used to present the theory meant that it could be treated only in a cursory fashion and without due consideration of competing theories.

To the untutored eye, it surely does appear that the sun crosses the sky above a fixed earth every day. And it may well appear to the untutored eye that homosexual men and women make no contribution to genetic fitness, that homosexuality cannot therefore possibly be heritable. And yet there are perspectives that can account both for durability of homosexuality across generations even if genetic research is unfinished in its investigations. Again, there may or may not be some genetic endowment that determines sexual orientation. There are good reasons to plead agnostic in regard to the state of sexual orientation science today. It is, however, important to point out that a microbial infection theory does not have automatic advantages over a genetic theory. The larger point worth making is that science by press conference can border on the irresponsible. While this may not be true for all science in all circumstances, I think there are special circumstances that set the threshold for the scientific study of sexual orientation higher than might be the case for other kinds of research.

The scientific literature is littered with false and unprovable theories about the origins of homosexuality. There have been so many false starts in regard to the study of homosexuality that the scientific community — and the public — have the right to expect tougher standards in the conduct of this science. Even if we grant for the sake of the argument that homosexuality could be the result of a microbial infection, the scientific community and the public deserves something better than merely laying out the logical possibility of the idea. The claim should be articulated in the strongest possible way, taking into account all competing hypotheses, and offering the strongest possible evidence. This is to say that if scientists want to propose a new theory, they should have done at least the preliminary work in credible scientific venues. It is too late in the historical day to believe that water-cooler hypotheses shed any light on homosexuality, especially when so much hangs in the balance. Who benefits from holding out in the public press the unsubstantiated idea that homosexuality could be the result of a microbial infection? Certainly neither the scientific community nor gay people.

References

1. Judith Hooper, "A New Germ Theory," Atlantic Monthly, February, 1999, pp. 41-49. See also Caleb Crain, "Did a Germ Make You Gay?," Out, August 1999, pp. 46-49.

2. Richard von Krafft-Ebing, Psychopathia Sexualis (New York: Stein and Day, 1965).

3. E.O. Wilson, On Human Nature (Cambridge: Harvard University Press, 1978).

4. See Michael Ruse, "Are There Gay Genes? Sociobiology and Homosexuality," in Noretta Koertge, ed., Philosophy and Homosexuality (New York: Harrington Park, 1985), pp. 5-34 and Michael Ruse, Homosexuality: A Philosophical Analysis (Oxford: Basil Blackwell, 1988).

5. Simon LeVay, "A Difference in Hypothalamic Structure between Heterosexual and Homosexual Men," Science 1991 (253): 1034-1037. This study is discussed at length in Simon LeVay, The Sexual Brain (Cambridge: MIT Press, 1993) and Queer Science: The Use and Abuse of Research in Homosexuality (Cambridge: MIT Press, 1996).

6. J. Michael Bailey and Richard C. Pillard, "A Genetic Study of Male Sexual Orientation," Archives of General Psychiatry 1991 (48): 1089-1096; J. Michael Bailey, Michael C. Neale, Yvonne Agyei, "Heritable Factors Influence Sexual Orientation in Women," Archives of General Psychiatry 1993 (50): 217-223. See also Richard C. Pillard and J. Michael Bailey, "A Biological Perspective on Sexual Orientation," and J.D. Haynes, "A Critique of the Possibility of Genetic Inheritance of Homosexual Orientation," Journal of Homosexuality 1995 (28): 91-113.

7. Dean H. Hamer, Stella Hu, Victoria Magnuson, Nan Hu, Angela M. L. Pattatucci, "A Linkage between DNA Markers on the X Chromosome and Male Sexual Orientation," Science 1993 (261): 321-327.

8. This sort of correlation did not hold up for women. See Angela M. L. Pattatucci, and Dean Hamer, "Development and Familiality of Sexual Orientation in Females," Behavioral Genetics 1995 (25): 407-420.

9. See Timothy F. Murphy, Gay Science: The Ethics of Sexual Orientation Research (New York: Columbia University Press, 1997). See also Edward Stein The Mismeasure of Desire (New York: Oxford University Press, 1999).