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The Complex Interaction Of Genes And Environment: A Model For Homosexuality
DR. JEFFERY SATINOVER
There is essentially no dimension of behavior which is not both environmentally and genetically influenced. Genes and environment interact in extraordinarily complex ways with each other, as well as among themselves to produce a final result; the environmental influences are multi-factorial and affect each other; in human behavior, the pertinent genes are also multiple. Furthermore, there are very few circumstances where free will plays little or no role in what we do. These facts are true of homosexuality as of all other dimensions of human behavior. Indeed, there are no features of human behavior which are not influenced in some fashion by our genetic makeup and no features of human behavior which are not influenced in some fashion by our environment.
Most people do not realize that the discovery that there is a degree of genetic heritability to homosexuality is a meaningless finding. It is being put forth to the public by activists as though it has great import when it actually has none. This is because there is no evidence (and it is highly unlikely that there ever will be any) that suggests that there are genes which code for homosexuality itself. In other words heritability of (or genetic influence on) a trait does not mean that the trait itself is genetically determined. This elementary fact of behavioral genetics is rarely explained and it seems counterintuitive to most people. Here is how it works:
No genes exist that code for becoming a basketball player. But some genes code for height and the elements of athleticism, such as quick reflexes, appropriate bone structure, height-to-weight ratio, muscle strength and refresh rate, metabolism and energy efficiency, and so on.any such traits have obvious racial distributions, so that more men of Bantu or Nordic stock (being taller) will be found on professional basketball teams than men of Pygmy or Appenzeller Swiss stock (being shorter).
Someone born with a favorable (for basketball) combination of height and athleticism is in no way genetically programmed or forced to become a basketball player. These qualities, however, certainly facilitate that choice. As a consequence the choice to play basketball has a clear genetic component, most evident in the very high heritability of height. Height, by the way, is also influenced by diet-mostly negatively in the sense that the maximum height is preprogrammed. The actual height, however, requires the cooperation of upbringing to be reached. In summary, the strong genetic predisposition to basketball playing does not mean that people do not choose-entirely-to play basketball.
The editors of Science devoted a recent issue almost exclusively to "Genetics and Behavior." In the opening editorial, Torsten Wiesel, president of the Rockefeller University, one of the leading international centers for genetics research, comments:
The recent identifications of the mutations underlying Huntington's disease demonstrates that neurological disorders can also be caused by a single aberrant gene. But many other neurological diseases, such as schizophrenia and manic-depression, are likely to have polygenic roots whose interaction with environmental factors will be highly complex.
It has long been known that schizophrenia clusters in families and identical twin studies have supported the belief that the susceptibility to schizophrenia has a genetic component. Yet it is also important to recognize that the genes which predispose one toward schizophrenia may not be expressed except under special environmental circumstances; for instance conditions of great stress. Indeed, understanding of how gene expression in brain cells is regulated by environmental experiences may serve as the foundation for the design of drugs or for preventive measures for better controlling gene expression patterns.
The operations of the brain result from a balance between inputs from heredity and environment-nature and nurture-and this balance should also be reflected in research into the biological basis of behavior. 
GENETICS AND BEHAVIORAL PROBLEMS - ALCOHOLISM
In the area of behavioral problems, the classic example of a similar phenomenon is alcoholism.
It has long seemed that problem drinking has a genetic component.  Even after social and family influences have been taken into account, evidence remains that when a gene or set of genes are present in an individual or family there is a much higher risk for serious alcoholism. Furthermore, certain national and transnational gene pools (Irish, Scandinavian, northern European in general) seem to be predisposed to alcoholism.
Researchers have long presumed that a specific gene might code directly for alcoholism itself, since that is the seemingly most obvious way to understand "heritability." Nonetheless, it always seemed strange that such an obviously counterproductive gene would exist. The same puzzle, of course, lurks behind the proposition that homosexuality is directly genetic.
For a while it seemed that the gene in question might be somewhat like the one that makes alcohol so problematic for Native Americans. In this particular racial pool the gene that directs the synthesis of the enzyme responsible for breaking down alcohol commonly codes for a different form of the enzyme than is found among Caucasians. The American Indian variant breaks down alcohol only very slowly; therefore alcohol rapidly accumulates. Serious intoxication can thus be caused by relatively small amounts of alcohol. But this theory proved to be a false lead. The Irish and the Nordics metabolize alcohol rapidly and well; those who drink heavily metabolize it even more rapidly.
As an aside, another example of how genes indirectly lead to behavioral patterns is found among Orientals. No gene exists that codes for a preference for an Oriental style of cooking. And yet careful study shows that there is a very strong genetic association to such a preference. This is because Orientals lack the gene that codes for the enzyme lactase, which breaks down the lactose found in all milk products. When lactose is not broken down, milk products cause diarrhea. Oriental cooking styles have thus developed around a milk restriction similar to that required by anyone with a lactose intolerance.
Returning to alcoholism, it turns out that the genetic makeup of Northern Europeans generally tends to code for an enhanced fight, flight response to a given stressor. Their nervous systems are more "high strung." Thus they react with relatively intense sympathetic nervous system arousal to a perceived threat.  This is experienced subjectively as anxiety. Alcohol is the original anti-anxiety agent. It produces a response in the brain almost identical to that of Valium or Xanax. 
People with this predisposition to intense anxiety responses are more likely to find their way into greater alcohol use  because for them alcohol gives a greater degree of emotional relief than it does to the more laid-back "Mediterranean" type. 
Why do Northerners have this disposition in greater proportion than Southerners? The answer lies in the observation that the most critical distinction for this aspect of human biology is not so much "North" versus "South" or even "warm" versus "cold" as "Polar" versus "Equatorial." Because 75 percent of the earth's land mass is found in the Northern hemisphere, this translates into a distribution of the various people-types corresponding mostly to the comparison North versus South, rather than the reverse, as in the Southern hemisphere.
At issue is not the location per se but the differing cycles of light found close to and far from the equator. The harsher climate and intermittently reduced intensity of light found nearer the poles is not only associated with differences in body build and skin color but also with differences in the nervous system. This fact is less surprising than it might seem because both skin and the nervous system derive from the same precursor tissue in the developing fetus. In brief, the Northern races have adapted to the harshness of their environment by generally developing the more easily stimulated nervous systems of, say, hunter-warriors than have the equatorial races.
In its pure form, this genetic type not only reacts psychologically with greater anxiety, but also responds somatically to stressors with intense physiologic responses such as increased heart rate and blood pressure, skin flushing, perspiring palms and soles, and so on. All these responses, subjective and physiologic, are mediated by the nervous system. Alcohol thus calms all of these by "calming" the underlying "nerves." 
Thus genetics strongly predisposes individuals toward alcoholism. And yet no genes specifically code for it. This seeming contradiction can be explained by the fact that some genes do code for the anxiety (fight/flight) response (an ancient, quite mechanical set of responses foundational to the nervous system of all animals) and under certain circumstances an especially intense response is adaptive. Those who carry such genes may be more likely to develop alcoholism than those who do not carry them. This does not mean, however, that alcoholism is itself directly genetic, natural, a good thing-nor, for that matter, that it is an illness in the strict sense of the word.
Of interest in comparing alcoholism to homosexuality is the fact that alcoholism is estimated to be between 50 percent and 60 percent heritable; homosexuality is estimated (even by activist researchers) to be at most less than 50 percent; it very likely considerably less. This even greater risk for alcoholism does not lead to the conclusion, however, that alcoholics are not responsible for controlling, changing, or stopping the behavior. We should also note that early enthusiasm over alcoholism being linked to a gene that coded for the D2 brain (dopamine) receptor proved to be as unfounded as all the other claims for behavioral genes. 
GENETIC INFLUENCES IN HOMOSEXUALITY
This association between a directly inherited trait (intensity of flight/fight response, level of anxiety) and a genetically unrelated behavioral pattern (alcoholism) not only provides an analogy for the possible meaning of the limited contribution of genetics to homosexuality, it may also point to at least one actual explanation for at least some instances of it. For some evidence is emerging that unusually intense anxiety responses are also associated with an increased tendency toward homosexuality.
The fact that multiple genes and multiple environmental factors interact with each other in differing ways over time (i.e., developmentally) adds further to the complexity, as does the fact that repetition and habit (which may be eschewed, more readily early than late) reinforce and exaggerate the direction that development takes. Furthermore, traits that are affected by multiple genes have multiple different patterns of inheritance depending on how many and which of the relevant genes are inherited and which not. For these reasons (especially the last) the more sophisticated researchers speak not of "homosexuality" but of "homosexualities," for depending on the precise mix of environmental variables and genes, the pattern of behavior as well as its entrenchment and resistance to change will be quite different.
Making the picture even more complex is the fact that homosexual behavior may emerge for an extended period of time and then disappear forever. Or, it may reapper once again later (or for the first time later). This important fact was statistically confirmed by the authors of Sex in America  (and of The Social Organization of Sexuality) who found that the majority of people who engaged in homosexual behavior did so transiently, predominantly when younger.
Long periods of homosexual behavior followed by a spontaneous change to exclusive heterosexuality suggest important developmental factors that affect broad sweeps of life. But homosexual behaviors may emerge and subside in short bursts as well, suggesting the effect of acute stress. (Those who have successfully emerged from homosexuality to live fully heterosexual lives can attest to this. They have learned that the reappearance of homosexual feelings, rather than being taken as marching orders, are merely symptomatic of other undealt with anxieties. When these are met squarely, the impulses subside ).
We can gain some insight into this complexity, and a deeper understanding what it really means to say that some behavior "has a genetic component" (and how far this really is from saying that it F "is genetic") by examining a type of diagram used by behavioral psychologists to illustrate the general relationship between genes and environment. The diagram is called a "threshold" diagram, because it illustrates the conditions necessary for an individual to "cross the threshold" and display the behavior in question.
Diagram 1 demonstrates one of a number of possible "types" of homosexuality associated with a given cluster of genes that interact with a whole host of behavioral and physiological variables (those causing unusual social anxiety, for example, or a particular body habits, as well as nervous system variations). This diagram illustrates a hypothetical class of people among whom homosexuality is 12 percent heritable. This "type" is comparable to the conservative end of heritability estimates for all (unselected, male) homosexuals based on the modest amount of currently available literature as referenced in the text.
Five different individuals, A through E are shown in the diagram, to be read as though locating one's position on a map:
Depending on where the person's innate disposition and environmental history places him, he will be more or less likely actually to be homosexual. In this case, in order for the pressure to be a homosexual to be very strong, the individual must inherit many of the genes and unless he has inherited 100 percent of them, the environmental factors must all add together in just the right way. If he has inherited less than 60 percent of the genes in this cluster, it is extremely unlikely he would turn to homosexuality regardless of environmental factors.
Persons A and B both have few of the genes so the pressure for them to become homosexual is quite weak, even when the environmental influences in that direction are strong (person A). Person E has inherited many of the genes, but the environmental influences are weak for him also, so he, too, experiences little pressure to become homosexual. Person E, for example, might experiment with homosexuality, but not stick with it even though he has the same genetic composition as D. Persons A, B, C and E all show some evidence of a genetic predisposition (E more than C more than A or B), yet none are likely to become homosexual.
Person D, on the other hand, has both a sufficient number of the genes in question and a sufficiently adverse environment. The pressure on him is great and he is therefore more likely to succumb. Nonetheless, the domain of heterosexuality lies close by, as it were, and it would not take all that much movement for him to "cross the line."
Diagram 2 represents another variant of homosexuality in which the heritability is about 25 percent. In this condition it takes less net environmental influence and a smaller percentage of the gene cluster to generate strong homosexual impulses. The homosexual "domain" is "more available" as it were. Under these circumstances, Person D is "deep within it" in the sense that the impulses he experiences are very strong and it will take much more for him to resist and emerge from this Type H homosexuality than from Type I.
Diagram 3 represents yet another variant of homosexuality in which the heritability is 50%. This degree of heritability lies at the upper limit of potential actual heritability of homosexuality based on the current literature as interpreted by activists. In this case, even person C with but a modest genetic loading might "cross the line." But so might he relatively easily cross back again. In fact, persons A, C and E, each with very different composites of environmental backgrounds and very different genetic loadings, is about equally close to the line. Different interventions would be called for, too, to help each remain in the heterosexual domain or cross back.
Person E, for example, with a high genetic loading but little environmental influence, might respond poorly to psychotherapy or other psychosocial interventions, but surprisingly well to medication, even by itself, person C might respond to individual (reparative) psychotherapy since the environmental factors in his background are relatively modest. Person A, however, who has little genetic loading, has, for example, grown up under such adverse circumstances say significant trauma (e.g., childhood sexual abuse) that more powerful (but non medical) interventions might be needed: group treatment such as is often helpful for trauma survivors, or spiritual healing.
Diagram 4 reexamines type H homosexuality to consider the effect of habit. Habit differs from the other environmental variables listed on the left because it has a large element of will at the beginning, but becomes more deeply embedded over time. Furthermore, it reinforces itself. It is therefore a far more complex and dynamic variable than are the others and should be considered separately (it cannot merely be added in to the others in some proportion because its effect changes over time.)
The diagram shows how habitual homosexual activity shifts the demarcation line ever leftward. Persons D and E, becomes progressively "deeper" into the homosexual domain as the years go by; person C, who started out essentially heterosexual may "become" homosexual over time as a consequence of repetition (not just of behavior, but of fantasy as well). The more deeply embedded the habit, of course, the more difficult it is to change. Given the findings in Sex in America that many more young people experiment with homosexuality and then give it up, this diagram illustrates the importance of not reinforcing, indeed of appropriately discouraging, homosexual behavior. This principle is lost to a view which considers homosexuality a preexisting, either/or phenomenon.
MAXIMUM NET EFFECT
Diagram 5 repeats Diagram 4, but demonstrates the effect of will. The truth is that the sharp demarcation lines are a convenient fiction. Actually, the lines are very fuzzy (further blurring the either/or view of homosexuality). One's determination and intent plays a significant role in whether homosexual behavior will be enacted or not. As the diagram illustrates, however, the merely willful determination to resist plays a larger likely role among individuals whose homosexual impulses are relatively modest. Habit, of course, will make the impulses progressively more difficult to resist.
Diagram 6 demonstrates the effect of treatment or of healing experiences that shift the boundary rightward, progressively weakening the homosexual impulses and decreasing the frequency of homosexual behaviors. Some people (e.g., person E.) will respond to treatment relatively easily; others (person D) will not. Realistically, even if enough research were done to determine the major types of homosexuality and their various interacting causes, and if different combinations of treatments were matched to these causes and combined, it will remain impossible to help all individuals. That is to say, the shaded area at the upper right may get smaller and smaller but will never shrink to nothing. On the other hand, every thoughtful form of treatment is likely to benefit some.
Diagram 7 represents the effects of current stress on homosexual impulses and behavior. Stress varies over time and is not "objective." What is stressful is that which is perceived and experienced as stressful and this will vary from person to person and over the course of a lifetime. In general, however, individuals with adverse backgrounds and/or a vulnerable constitution will have a low threshold for finding experiences stressful. They will be at greatest risk for a movement or relapse into homosexual impulses or behavior for a time, as illustrated by person A. Hence, the relatively high rate of homosexual acting-out among adolescents.
The shading in Diagram 8 roughly demonstrates the fact that high risk homosexual behavior correlates closely with the severity of the environmental and other factors, e.g., habit and stress. The more to the upper right one is shifted by the factors (the more to the lower left the boundary is shifted) the more dangerous homosexual behavior is apt to be. Roughly speaking, the more deeply embedded the homosexual habit, and the more it is a response to stress, the more likely it is to be associated with promiscuity, lack of knowledge of partner's HIV status, anal intercourse and unprotected intercourse.
At present, behavior change programs that accept homosexuality as an either/or, unchangeable phenomenon, but wish to lower high-risk behavior are engaged in efforts at pushing the individual from the right hand comer down and to the left yet not across the (fuzzy) boundary into predominantly heterosexual behavior.
PUTTING THE PIECES TOGETHER
It may be difficult to grasp how genes, environment, and other influences interrelate to one another, how a certain factor may "influence" an outcome but not cause it, and how faith enters in. The scenario below is condensed and hypothetical, but is drawn from the lives of actual people, illustrating how many different factors influence behavior.
Note that the following is just one of the many developmental pathways that can lead to homosexuality, but a common one. In reality, every person's "road" to sexual expression is individual, however many common lengths it may share with those of others.
From communities of faith that turn to him in understanding, offering not only moral guidance but genuine healing, he will gain much in addition. Most importantly, the love he sought so vainly when young and finally turned away from he will find in the arms of a loving God. Those for whom this is no mere formula but a living reality are truly blessed, whatever their wounds. And he will find too that the presence of this love makes it possible to lay those old defenses down and face fearlessly the wounds that have inflicted so much pain and distorted so much of his life over so many years. For many, this is the only circumstance in which it is possible to lay their defenses down.
Of course the old wounds will not simply disappear, and later in times of great distress the old paths of escape will beckon. But the claim that this means he is therefore "really" a homosexual and unchanged is a lie. For as he lives a new life of ever-growing honesty, and cultivates genuine intimacy with the woman of his heart, the new patterns will grow ever stronger and the old ones engraved in the synapses of his brain ever weaker.
In time, knowing that they really have little to do with sex, he will even come to respect and put to good use what faint stirrings remain of the old urges. They will be for him a kind of storm-warning, a signal that something is out of order in his house, that some old pattern of longing and rejection and defense is being activated. And he will find that no sooner does he set his house in order that indeed the old urges once again abate. In his relations to others as friend, husband, professional he will now have a special gift. What was once a curse will have become a blessing, to himself and to others.
If he is fortunate enough to be able to place all this in the context of faith, then he will also find that he has traveled far along the ancient pathway toward sanctification. This is just as when the angel put Jacob's hip out of joint and then blessed him, transforming him forevermore into Israel. On this road he will always have as his companion the Great Companion. And perhaps because of this he will find his footing a little more surely than those who are skeptical that such a companion walks invisibly at their side, too.
Satinover, M.D., Jeffrey. The Complex Interaction Of Genes And Environment: A Model For Homosexuality. NARTH Annual Conference, Saturday, 29 July 1995.
Reprinted with permission of Narth.
Jeffrey Burke Satinover, M.D. is a psychiatrist and psychopharmacologist in private practice in Westport, Connecticut. He is a diplomat of the C.G. Jung Institute of Zurich and of the American Board of Neurology and Psychiatry, and past-president of the C.G. Jung Foundation of New York. He is a former Fellow of the Yale Child Study Center and former William James Lecturer in School of Divinity at Harvard University. He has twice been the recipient of the Lustman Research Award in Psychiatry from Yale University. He is the author of many scientific and psychoanalytic articles. He is the author of Homosexuality and the Politics of Truth.
Copyright © 1995 NARTH