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As you will recall, there are three disputed propositions at the heart of the debate over homosexuality today:

1. Homosexuality is normal;

2. Homosexuality is innate, or inherited;

3. Homosexuality is irreversible.

In this chapter and the three that follow we will address the second point: "Is homosexuality innate and inherited?" As we will, see the very way the question has been framed by gay activism and its media promoters contributes seriously to our confusion.

Defining Our Terms

Let us start by defining our terms. When we analyze and discuss the causes of a given behavioral trait, we find that each cause belongs to one or more of the following categories:

Genetic

Genetic traits are those (like eye color, for example) that are coded for us by genes. We can think of each human gene as a book that provides a complex set of instructions for the synthesis of a single protein. These proteins are then responsible for forming and operating everything else in the body.

The entire collection of genes that provides codes for a human is vast. Therefore it is divided into twenty-three pairs of matched, physically distinct structures called chromosomes. We can think of them as matching libraries that contain and catalogue two copies of every required "book" (gene) in a specific order that does not vary from person to person. Chromosome libraries exist in pairs because each person actually has two instructional genes for every protein, receiving one of every gene from his mother and another from his father. The unvarying order in which the genes are catalogued allows each one of the millions and millions of genes to be matched to its proper companion during reproduction.

Any genetic trait inherited from our parents may be:

1. Expressed, as when the gene that codes for it is dominant and we have inherited at least one such gene from each parent (brown eyes; brown is dominant); or as when the gene that codes for it is recessive and we have inherited the same gene from both parents (blue eyes; blue is recessive).

2. Not expressed, as when the gene that codes for it is recessive and we have inherited that gene from only one parent (brown eyes; blue is recessive and therefore not expressed).

3. Partially expressed, as when—whether the gene that codes for it is dominantor recessive—one or more other genes or other factors influences its expression. We may or may not have some or all of these other genes, or we may be only partially exposed to these other factors (green eyes).

Genetic traits are truly and directly inherited. All traits with which we are born tend to be put into this category, sometimes incorrectly, such as those that are innate but not genetic.

Understanding behavioral traits influenced by genetics becomes more complex. Unlike simple traits, such as eye color, that are close to being programmed by a single gene, most behavioral traits with a genetic background are programmed by multiple genes. Because these genes are rarely inherited together, their possible forms of expression fall into a complex spectrum. Behavioral traits that are influenced by genetics are therefore never eitherlor conditions.

Innate

Some traits may be merely innate, meaning the individual is born with them. But innate traits may be:

1. Genetic, as outlined above; or
2. Not genetic, but caused by intrauterine influences. These are traits (such as the degree to which a fetus develops masculine or feminine sexual characteristics) that are influenced by various aspects of the environment in the womb. Hormones, infections, exercise, general health, the ingestion of licit or illicit drugs, and many other variables influence this environment. Thus one may be born with a trait that is innate, but not genetic.

Familial

Other causes of traits may be familial, meaning that they tend to be shared by members of the same family. Familial traits may be:

1. Genetic. Because they have the same parents, brothers and sisters are more likely to share a high percentage of similar genes than would unrelated individuals.
2. Innate, but not genetic. Sharing the same mother, certain typical factors may remain constant or similar for all children born to her. Examples include the effect of her dietary habits on her unborn children, the fact that she smokes, or her general health.
3. Not innate, but environmental. To an extent greater than between individuals from different families, individuals raised in the same family share a similar environment. These include the physical, emotional, and moral influences. Thus family members may share some traits that are neither genetic nor innate but that are nonetheless transmitted from one generation to the next by influence.

Biological

Another term that may be used to describe a trait is biological. A biological trait is rooted in an organism's physiology, rather than its psychology. With respect to behavioral traits, this distinction suggests a dichotomy comparable to the difference between "hardware" and "software" in the domain of computer science. Biological traits may be:

1. Genetic; or
2. Innate but not genetic; or
3. Environmental and familial but not innate (for example, the effect of a virus that has taken root among the members of a household); or
4. Environmental and not familial and possibly innate but maybe not (for example, the effect of a toxin in the environment at large, depending on whether its baleful influence is felt pre- or postnatally).

Environmental

Additionally, the cause of a trait may be purely environmental but not biological, at least insofar as we do not attend to the biological dimension. Examples include the influence on behavior of the values, standards, habits, economic status, and so on, of a family or society.

Direct versus Indirect

Finally, any of these causes may be direct or indirect. That is, the cause may:

1. Lead directly to the trait. Whether we are speaking of genetic or nongenetic, innate or noninnate, biological or nonbiological influences, the cause may directly produce the trait itself, as when genes cause blue eyes or when smoke causes a cough.
2. Lead indirectly to the trait. Because of what the influence causes directly, the individual finds it desirable to choose a particular trait. This is seen, for example, when tall athletic individuals become basketball players or when short athletic people become jockeys.
3. Furthermore, all of these causes may combine and influence one another in highly interdependent ways, mutually influencing each other throughout a lifetime. Behavioral traits, as opposed to simple, single-gene physiologic traits such as eye-color, always interact in this way.

In summary, the question concerning all behavioral traits, such as homosexuality, cannot be "Is such and such genetic?" Rather we must ask, "To what extent, respectively, is such and such genetic and nongenetic, innate and noninnate, familial and nonfamilial, environmentally determined and not, direct and indirect? In the course of development, when do which influences dominate and how do their interactions affect one another?" We need to keep this sobering caution in mind as we clarify what medical science has and has not learned about the subject of homosexuality.

Most mental states, normal or not, have long been presumed to be of psychological origin because we have not been able to understand the biology. We simply did not have the information or skills to intervene in a purported disease of the brain whose primary manifestations were psychological. But neuroscience research techniques have proliferated. We now can dissect out at least some of the specific mechanisms, down to the level of molecules, that play a role in many conditions previously thought to be purely psychological. Although this research has already produced many dramatic benefits, we are far from having a precise blueprint of the various causes of any psychiatric condition.

Demonstrating that any behavioral state, let alone one so complex, diverse in its manifestations, and nuanced as homosexuality, is not only biological but genetic is well beyond our present research capacity. One psychiatric researcher who was tired of the overblown claims of people trying to label everything as "genetic," calculated what would be required to confirm a behavioral trait as genetic. He projected that "If the trait was 50 percent heritable and each family in the [initial] study had ten members (4 grandparents, 2 parents and 4 children), detecting one of the genes would require studying . . . 2000 people. Replicating that finding would require studying . . . another 8000 people. To find and confirm each additional gene (for a polygenic trait), researchers would need to go through the whole business again. "Suddenly you're talking about tens of thousands of people and years of work and millions of dollars." No study of homosexuality has come even remotely close to these requirements.

In the case of schizophrenia, for instance, such research efforts have only now begun to yield somewhat reliable results after over forty years of effort. But even after so much research, the major questions - Mat causes schizophrenia? How does this illness affect the nervous system? What environmental cofactors are critical to its appearance? What interventions might be curatives.— remain almost entirely unanswered.

Different studies claim to show anywhere from 40 to 90 percent heritability for schizophrenia. Researchers have made numerous claims to have found a meaningful "genetic linkage" to a particular chromosome, only being forced to retract them in every case.{1} The vastly more complex problem of finding the genes themselves or the specific DNA base pairs among the millions on the chromosome has been compared to finding a needle, not in a haystack, but in the ocean.

In the case of homosexuality, only a handful of barely adequate studies on a small number of people have been conducted in the past few years. We will explore these more fully in the chapters that follow. But first it is important to lay out three important limitations that are already beginning to emerge from this research. All are quite consistent with what we already know about the biological and genetic bases of other conditions.

First, like all complex behavioral and mental states, homosexuality is multifactorial. It is neither exclusively biological nor exclusively psychological but results from an as-yet-difficult-to-quantitate mixture of genetic factors, intrauterine influences (some innate to the mother and thus present in every pregnancy, and others incidental to a given pregnancy), postnatal environment (such as parental, sibling, and cultural behavior), and a complex series of repeatedly reinforced choices occurring at critical phases in development.

Second, male and female homosexuality are probably different conditions that arise from a different composite of influences. Nonetheless, they have some similarities.

Third, "homosexuality" is very poorly defined. Our use of this one term creates the false impression of a uniform "gay" or "lesbian" condition and culture. It obscures the reality that what we are studying is a complex set of variable mental, emotional, and behavioral states that are caused by differing proportions of numerous influences. Indeed, one of the chief characteristics of the gay lifestyle is its efflorescence of styles and types of sexuality. Thus many of the more careful researchers in the field, usually nonactivist, refer to ''homosexucll~ties.''

The belief that homosexuality is "genetic" tends to translate into a more positive attitude toward it. Gay activists know this and research studies confirm it:

"To measure the relationship between beliefs about the determinants of homosexual orientation and attitudes toward homosexuals, we asked 745 respondents in four societies about their beliefs concerning the origins of homosexual orientation. Analysis indicated that subjects who believed that homosexuals are "born that way" held significantly more positive attitudes toward homosexuals than subjects who believed that homosexuals choose to be that way and/or learn to be that way{2}."

Similarly:

"One hundred and five . . . subjects . . . were exposed to one of three treatment conditions.

Subjects in the experimental group read a summary article of current research emphasizing a biological component of homosexual orientation. Subjects in one control group read a summary article of research focusing on the absence of hormonal differences between homosexual and heterosexual men. Subjects in another control group were not exposed to either article. All subjects completed the Index of Attitudes Toward Homosexuals. As predicted, subjects in the experimental group had significantly lower{3} scores than subjects in the control groups.{4}

This "public relations" effect has precipitated a recent media outpouring on the biology and genetics of homosexuality. Starting in 1991, media all across the country have trumpeted the discovery of a series of supposed brain differences between homosexuals and heterosexuals. Commentators claim that these findings will halt any remaining uncertainty that homosexuality is either a choice or a consequence of factors in upbringing. In this light, to continue supporting anything less than full acceptance of homosexual behavior would be proof positive of prejudicial hatred.

The outpouring began in August of 1991 when a San Francisco neuroanatomist, Simon LeVay, published an article in Science. It reported his finding that a localized cluster (a "nucleus") of cells in the brains of "homosexual" men was twice as large by volume on autopsy as in "heterosexual" men.{5} ("Homosexual" and "heterosexual" are in quotations because in this study the definitions of each were extremely imprecise, nor was there any way of verifying sexual orientation as the subjects were dead.)

But this was not the first such discovery. One year before a group reported in Brain Research that they had found a similar difference—in both volume and number of cells—in a different brain nucleus.{6} The media, however, did not report this first study because Brain Research, unlike Science, is read only by neuroscientists. And in contrast to journalists, the neuroscientists understood the research and its limitations and refrained from grand pronouncements.

The specifics of these findings are not as important as realizing that unless group differences are dramatic, individual studies of such differences mean almost nothing. It would take hundreds, perhaps thousands, of such studies before meaningful trends emerge. Thus it is wrong for the media, or parties with vested interests, to argue the significance of something so complex as human nature on the basis of one or a handful of findings and then derive public policy implications.

Furthermore, even if such brain differences were convincingly demonstrated to be present, their significance would be on a par with the discovery that athletes have bigger muscles than nonathletes. For though a genetic tendency toward larger muscles may make it easier to become an athlete (and therefore such an individual will more likely be one) becoming an athlete will certainly give one bigger muscles. One researcher comments: "The brain's neural networks reconfigure themselves in response to certain experiences. One fascinating NIH study found that in people reading Braille after becoming blind, the area of the brain controlling the reading finger grew larger."{7}

Press accounts, in contrast, are often written so as lead one to assume that brain differences must be innate and unchangeable, especially differences in the number of cells as contrasted with the simple volume occupied by a collection of cells. We tend to think of the mind as "software" and the brain as "hardware," the former plastic and changeable, the latter fixed at birth. We have used this analogy already to good advantage.

But the analogy breaks down at a certain point. Various processes go on throughout life: the selective death of brain cells in response to training or trauma, the establishment of new connections between cells, dramatic increases or decreases in the "thickness" of connections between cells as a result of learning, the loss of interneuronal connections through "pruning." Very unlike our modem computers, the brain's software is its hardware.

We know from animal studies that early experience and especially traumatic experience that especially applies to the childhood histories of many homosexuals, alters the brain and body in measurable ways. Thus infant monkeys who are repeatedly and traumatically separated from their mothers suffer dramatic alterations in both blood chemistry and brain function.{8}

One major theory about why some people become depressed and others do not holds that under conditions of early trauma, a genetically based susceptibility to stress creates a greater likelihood of intense stress-responses later in life.{9} This "vulnerability" is represented physiologically as actual alterations in the brain. And because what is experiences as "stressful" depends on one's subjective interpretation of events, the brains in individuals with the same genetically determined biology may respond differently. One may demonstrate no brain changes; another may demonstrate very significant changes.{10} Thus the editor of Nature commented on the LeVay research: "Plainly, the neural correlates of genetically determined gender are plastic at a sufficiently early stage . . .. Plastic structures in the hypothalamus [might] allow . . . the consequences of early sexual arousal to be made permanent."{11}

And of course all this presumes that the research itself was of high quality. But two prominent geneticists, Paul Billings and Jonathan Beckwith, writing in Technology Review (published at the Massachusetts Institute of Technology) write: LeVay "could not really be certain about his subject's sexual preferences, since they were dead." His "research design and subject sample did not allow others to determine whether it was sexual behavior, drug use, or disease history that was correlated with the observed differences among the subjects' brains.{12} LeVay's very method of defining homosexuality was very likely to create inaccurate or inconsistent study groups."{13}

Because all human behavior is related in some way to genes, we can nonetheless guess that one day higher quality research will find genetic factors that correlate to homosexuality. But remember, one ofthe fundamental principles of research is that correlation does not necessarily imply causation. With respect to whatever genetic or biological factors are correlated to homosexuality we will need to be very careful to understand what they mean and indeed, how limited the implications really are.

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{1}For an excellent nontechnical critique of the limitations of genetics research into many areas of human behavior, see Horgan, J. (June 1993~. Eugenics Revisited, Scientific American' pp. 12331.

{2}Ernulf, K. E., Innala, S. M., and Whitam, F. L. (1989) Biological Explanation, Psychological Explanation, and Tolerance of Homosexuals: A Cross-National Analysis of Beliefs and Attitudes, Psychological Reports 65, pp. 1003-10 (1 of 3).

{3}A lower score on this scale means a less negative attitude toward homosexuality.

{4}Piskur, J., and Degelman, D. (1992) Effects of Reading a Summary of Research about Biological Bases of Homosexual Orientation in Attitudes Toward Homosexuals, Psychological Reports 71, pp. 1219-25 (part 2 of 3).

{5}LeVay, S. (1991). C`A Difference" In Hypothalamic Structure Between Heterosexual and Homosexual Men, Science 253, pp. 1034-37.

{6}Swaab, D. And Hofman, M. (1990~. An Enlarged Suprachiasmatic Nucleus in Homosexual Men, Brain Research 537, pp. 141-48.

{7}Klivingston, K. Assistant to the President of the Salk Institute, cited by K. Lansing in Homosexuality: Theories of Causation, Reorientation and the Politics and Ethics Involved, Proceedings of the 1993 Annual Scientific Meeting of the National Association for Research and Treatment of Homosexuality, p. 50.

{8}Gabbard, G. (1992). Psychodynamic Psychiatry in the "Decade of the Brain," American Journal of Psychiatry 149, (8), pp. 991-98.

{9}Post, R. (1992). Transduction of Psychosocial Stress into the Neurobiology of Recurrent Affective Disorder, American Journal of Psychiatry 148, (8), pp. 999-1010.

{10}Gabbard, Psychodynamic Psychiatry.

{11}Maddox, J. (September 1991). Is Homosexuality Hardwired? Nature 353, p. 13.

{12}Ibid., p. 60.

{13}Ibid., p. 61.

Photo credit: Robert Satter

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Updated: 20 September 2004