The Causes of Homosexual Behavior

By Dr. J.D Robertson Posted: Thu. Feb 1st 1996
The issue that divides the various groups is the one of cause. What specifically causes homosexual behavior? Dr. J.D. Robertson, a licensed psychologist, examines both the "nature" and "nurture" points of view and provides a well balanced conclusion based on the latest scientific research.

When discussing the causes for homosexuality, Christians and churches run the gamut. Morally, the extremes are represented by the view that homosexuality is not condemned in Scripture as opposed to the view that homosexuality is condemned in Scripture. Concerning causes, researchers run an even more complicated course: homosexuality is caused completely by genetic factors; homosexuality is caused by a complex combination of genetic factors with certain "high risk" scenarios from the environment which set a predisposition for developing a homosexual orientation; homosexuality is caused completely by environmental conditions during childhood and adolescent development; homosexuality is completely a choice.

Much of the discussion involves two "oldie goldies" from developmental research - nature versus nurture. This issue involves how much of who we are resides in our nature - biology or genetic endowment - and is predetermined, as opposed to how much of who we are depends on how we were nurtured - childrearing practices from significant others and shaping from our unique environments - which mold us in ways that we learn and, therefore, may be unlearned. Although the verdict is certainly not in, we will attempt to explore the rationale for maintaining homosexuality has genetic origins, as well as the argument that homosexuality is environmental.


It seems we are bombarded with study after study in the mainstream media reporting that homosexuality is inherited genetically - it is someone's nature. People have no more control over their sexual preference than they do their eye color. Dr. John Money put it this way, "Despite popular assumptions, homosexuality, heterosexuality, and bisexuality are not preferences. Each is a sexuoerotic orientation or status. They are no more chosen than a native language is."1

David Myers maintains, "There is a growing agreement that sexual orientation is neither willfully chosen nor willfully changed. Sexual orientation in some ways is like handedness: most people are one way, some the other. Few are equally ambidextrous. Regardless, the way one is endures."2

He reports that Kinsey Institute interviews failed to discover any psychological cause of homosexuality. After outlining several theories involving environmental causes of homosexuality, Myers concluded "The bottom line of these conflicting theories is that after 100 years of research, the determinants of sexual orientation remain, for now, a mystery.

New research hints that the mystery's eventual solution may be at least partly biological."3

Researchers report that homosexuality runs in families. Richard Pillard and James Weinrich recruited single men between 25 and 35 who had at least one living sibling. They found that among the brothers of heterosexual men, only about 4% were homosexuals, as opposed to about 18% of the homosexual's brothers, who were also homosexual. Reviewers said, "The authors point out that their study could not show whether heredity or upbringing were more important."4

Richard Pillard has continued his studies of homosexuality and families. He has found homosexuals to have homosexual siblings at 4-5 times the rate of the heterosexual population. Also homosexuals appear randomly in the birth order, which indicates a possible genetic link rather than environmental influences embedded within family dynamics. In addition, his studies have found "gender nonconformity" in childhood play among homosexuals, which poses problems for some environmental theories which maintain homosexuality emerges from adolescence.

His most compelling work was research conducted with Michael Bailey that had to do with comparing monozygotic (identical) twins with dizygotic (fraternal) twins, and adopted brothers with biological brothers. The identical twins, those having identical genetic blueprints, had the highest concordance rate which turned out to be 52%. Fraternal twins, those who are dizygotic and no more alike genetically than other biological siblings, had the same concordance rate as other biological siblings (22%). Adopted brothers, who shared the same family environment but with different genetic backgrounds, had the lowest concordance rate in the study (11%).

The greatest case for genetic influence in twin research comes when a researcher can observe identical twins, separated soon after birth, and reared apart in different environments. Pillard points out how rare such cases are, and how much rarer are those involving homosexuality. "Nevertheless, Thomas Bouchard has identified two such cases in the Minnesota Twin Study: a pair of male twins in which both were gay, and another in which one was gay and the other heterosexual with some incidental homosexual contacts."5 Bailey and Pillard have a new study of lesbian twins that will be published soon where they have obtained similar results.6

Dovetailing with Pillard's findings concerning "gender nonconformity" in homosexual childhood play, Bernard Zuger has followed 48 boys who demonstrated effeminate behavior from as early as 3-6 years old from the 1960's through 1984. He found that at least 35% of the participants were clearly homosexual in adulthood. "The author considers it unlikely that the direction of sexual development could be changed in such boys even if it were desirable. He suggests explaining this to parents so they will not be made to feel guilty about something for which they are not responsible."7

Similarly, Dr. Richard Green of UCLA has studied gender-atypical play and concludes that such behavior in preadolescent boys reflects a homosexual orientation 75% of the time. If these studies are correct, they demonstrate powerful roots to homosexual orientation long before homosexual behavior. University of Wisconsin researcher Robert Goy has demonstrated that gender-atypical play can be created through hormonal manipulation in monkeys, which indicates the possibility that gender-atypical play in children may also have hormonal roots.8

The Knoxville News-Sentinel picked up an Associated Press story and on August 1, 1992, ran the headline "Study Links Brain Size to Sexual Orientation." The story summarized a piece of research from the UCLA School of Medicine where researchers discovered "a brain structure called the anterior commissure to be 34% larger in homosexual males than in heterosexual males."9 As a result, this study "adds weight to the theory that sexual orientation is not a matter of choice, but a function of biological design or development."10 These stories seem to be a daily occurrence on radio and television news reports, as well as in newspapers and magazines.

Chief among researchers studying brain differences is Simon LeVay, a biologist at the Salk Institute in San Diego. In a small sample involving the brain tissue from 19 homosexual men, 16 presumed heterosexual men, and 6 women, he discovered a difference in size of a brain area called the third interstitial nucleus of the anterior hypothalamus (INAH 3) between homosexual and heterosexual men. He observed that the area was the same in women and homosexual men, but more than twice the size in heterosexual men. LeVay recognizes some problems with the study and allows that the brain differences may be the result of homosexuality rather than the cause. Still brain differences have been observed and demonstrated among rats and monkeys which lends credibility to the findings.11

Dr. Earl Wilson considers the evidence and asserts, "...homosexual behavior can be created in the laboratory by the alteration of biochemical conditions. This cannot be denied."12

He cites two examples: stress during pregnancy has demonstrated demasculinizing effects on male rat pups, and the ingestion of barbiturates by a pregnant female will demasculinize male rat pups. Likewise, high levels of androgens before birth will tend to masculinize female rat pups. Hence the inference is, "too high a testosterone level in utero may contribute to lesbianism in females and too low a testosterone level may contribute to homosexuality in males."13 This all derives from the Adam/Eve Principle of prenatal hormonalization. Fundamentally the principle refers to the fact that sexual differentiation requires hormonalization. If the proper hormones are not secreted at the proper time the child will be female. The male gender requires hormonalization, which is what prompts Gary Smalley to say, hopefully with tongue-in-cheek, that men are brain damaged.14 Understanding the Adam/Eve Principle makes it easier to accept that something can go wrong chemically due to maternal stress and set up predispositions as a result of faulty hormonalization (not enough for males, or accidentally hormonalizing females).

Further evidence for prenatal hormonalization comes from Dr. John Money's 1984 study of CAH women. CAH involves an enzyme defect which results in the adrenal gland producing androgens rather than the needed substance (cortisol), hence the fetus is flooded with male hormones. In Money's study, 37% of the CAH women identified themselves as lesbian or bisexual as contrasted to current estimates of 2-4% in the general population.15

Pillard and Weinrich hypothesize that homosexual men undergo complete masculinization because they are genetically male; however, they may not complete the defeminization process. Males require androgens to prompt masculinization and an inhibiting hormone to defeminize them. The researchers maintain that homosexual men were masculinized by the androgens, yet not fully defeminized, creating a male with female aspects and homosexual orientations.16 The gender atypical play studies are usually cited as support of this theoretical viewpoint.

Although there is clear evidence of some biological link to homosexuality, it is wise to proceed with caution. Meier, Minirth, Wichern, and Ratcliff maintain that even if a biological root was proven, it would be a mistake to blame behavior on genetics. "While our genetic makeup does have a powerful effect upon us, we are not determined solely by our genes."17

Chandler Burr offers a statement by William Byne, "If the prenatal-hormone hypothesis were correct, then one might expect to see in a large proportion of homosexuals evidence of prenatal endocrine disturbance, such as genital or gonadal abnormalities. But we simply don't find this."18

Dr. Earl Wilson quotes Dr. John Money as saying, "...sexual orientation is not under the direct governance of chromosomes and genes, and that, whereas it is not foreordained by prenatal brain hormonalization it is influenced thereby, and is also strongly dependent on postnatal socialization."19 He also quotes Money as stating, "With respect to orientation as homosexual or bisexual, there is no human evidence that prenatal hormonalization, alone, independently or postnatal history, inexorably preordains either orientation."20 Hence research suggests there is a predisposition for sexual orientation before birth; however, it also suggests there is a complicated group of variables and their interaction involved and predisposition does not entail determination.

At least for the moment, genetic causes are compelling but inconclusive. Bearing this in mind concerning the "nature" studies, the consideration of arguments advanced by the "nurture" proponents can be just as compelling, and alas, just as uncertain.


As much as it seems we are bombarded with study after study that reports homosexuality as nature, we are equally flooded with experts who claim it is properly investigated in family dynamics or other environmental situations - the domain of nurture. These experts maintain that homosexuality is learned, and can be unlearned.

Modern environmental arguments for the origins of homosexuality usually cite the works of Sigmund Freud. He believed homosexuality originated in early childhood fixations and regression. 21 Based on Freud's views on arrested sexual development, psychoanalytic theorists came to the conclusion that families with weak, passive, or distant fathers, and strong, controlling, or domineering mothers might produce homosexuality in male and female children. The thinking is that the mother dominates the son who has no strong male role model to learn from. As the boy develops, he becomes insecure in his gender identity and ability to relate to the opposite sex and therefore identifies with his mother rather than his father. In contrast, girls fail to learn to relate to the opposite sex because of the father's rejection and turn to homosexuality because they are more comfortable with women.22 The problem with Freud's views is that there seems to be little empirical research to substantiate his opinion. As a result, "Most psychotherapists today reject this account; they consider homosexuality a variation rather than a perversion of or a deviation from a normal course of development."23 Dr. Earl Wilson points out that Freud's viewpoint seems to have face validity, yet it cannot account for the current percentages of homosexuals. "The majority of the persons I have seen who struggle with same-sex preference have not had rejecting parents of the opposite sex."24

A different twist on Freud's point of view comes from Elizabeth Moberly, who is persuaded that homosexuality actually originates in relational problems with the same-sex parent rather than problems with the opposite-sex Parent. She maintains that homosexuality is an unconscious attempt to restore the bond or attachment with the same-sex parent. In other words, the homosexual experienced a disruption or severe stressors in the relationship with the same-sex parent and is attempting to meet early bonding needs through sexual relationships with same-sex individuals. In fact, Moberly suggests the development of non-sexual relationships with same-sex individuals as therapy for homosexuals who wish to become heterosexual. 25 "Moberly writes, '...From amidst a welter of details, one constant underlying principle suggests itself: that the homosexual - whether man or woman - has suffered from some deficit in the relationship with the parent of the same sex; and that there is a corresponding drive to make good this deficit - through the medium of same-sex, or 'homosexual' relationships."'26 Wilson describes this process as a "reparative urge, a desperate effort to have needs met."27 Same-sex love is a normal human need typically supplied through the same-sex parent in a non-sexual way, however, Moberly maintains this need was distorted and the pursuit of the same-sex love in a sexual relationship introduces an inappropriate method for meeting this essential need. In response to Moberly's views, Wilson offers "I have discovered that the homosexual condition in a very high percentage of the counselees with whom I work can be explained by Moberly's theory. I do not believe it explains all homosexual causality or behavior."28

Dr. David Seamands says, "What actually causes homosexuality is a matter of considerable debate." 29 He identifies the two dominant theories of causality as genetic and environmental, and then asserts, "There is now a general agreement that it is not something genetic or hormonal." Dr. Seamands covers several environmental scenarios which are embedded in problems in the parent-child relationship, as well as early sexual experiences. He cites these examples as not exhaustive of causes, but illustrative of how the roots for homosexuality are usually found in family or social situations during development.

Dr. Gary Collins writes, "While many homosexuals do experience disruptions in parent-child relationships, others do not. Children in the same family do not all become homosexual even though there may be similar parent-child relationships." 30

However, certain family relationships have been shown to relate to homosexuality and Dr. Collins lists several scenarios cited by LawrenceJ. Hatterer:31

  • Mothers distrust or fear women and teach this to their sons.
  • Mothers distrust or fear men and teach this to their daughters.
  • A son is surrounded by too many females (mothers, sisters, aunts), but he has limited contact with adult males, thus he learns to think and act like a girl.
  • Parents who wanted a daughter but instead have a son subtly raise the boy to think and act like a girl (a similar situation arises when parents wanted a son but instead have a daughter); in both cases the child has great confusion about sexual identity and orientation.
  • A son is rejected or ignored by his father and hence feels in- adequate as a male and unsure how males relate to females.
  • A daughter is rejected by her mother and hence feels inadequate as a female, thus she can't relate well to males.
  • Both parents are afraid of sex, unwilling to discuss it in the home, or strong in their condemnation of sex; in all of this the child gets a distorted view of sex and as a result struggles with heterosexual adjustment.
  • A mother (or father) is so overindulgent that the child is overly attached to the parent, unable to break away, and convinced that no mate could ever compare with the opposite-sex parent.32

Other situations discussed by Collins include early molestations or homosexual experimentation that is eventually internalized, fear (for whatever reason) of the opposite sex, or conscious, willful choice of homosexuality. It would be difficult to make the case that early sexual abuse, molestation, or same-sex experimentation leads to homosexuality because there are too many heterosexuals who have had those experiences. However, for some people these experiences may be critical in ultimately deciding they are homosexuals and many people who work with homosexuals note the presence of early sexual experiences. Fear of the opposite sex may arise from rejection or embarrassing situations among other possibilities. The rationale for this viewpoint involves awkwardness, uncertainty, insecurity, or discomfort with the opposite sex, hence retreating to relationships with same-sex individuals. The idea of deliberate choice is advanced by authors and speakers, yet professionals and homosexuals tend to disagree. Collins maintains, "Sexual attraction to the members of one's own sex rarely if ever comes as a willful and conscious decision." 33 The realization of one's attraction to same-sex individuals usually produces anxiety or disbelief because it is so disturbing. Typically there is a long period of denial and attempts to feel comfortable heterosexually and hiding one's true feelings until eventually accepting the homosexual orientation. Therefore most professionals and homosexuals find it difficult to believe that a majority of homosexuals choose the lifestyle deliberately.

Wilson outlines the social learning theory's explanation for homosexuality. Social learning theory focuses on learning through observation and imitation. It essentially accepts operant conditioning principles, especially reinforcement, but adds cognitive components to the classic behavioral perspective and emphasizes observational learning. Wilson cites Hamachek's discussion of sexual behavior: "There seems little question that the basic components of sex-typing are undoubtedly acquired at home, largely through imitation of, and identification with, the parent of the same sex."34 Fundamentally, children observe parents and other adults, as well as observing and participating with peers in sex-typing behavior. This begins very early and these experiences may influence sexual orientations long before adolescence. As children develop sexual behavior, some is reinforced and thereby encouraged, while some meets with negative consequences and discouraged. Reinforced behavior increases in frequency while behavior resulting in unpleasant consequences tends to decrease. The social learning perspective maintains that unwittingly homosexuals may have been reinforced for same-sex preferences and punished for opposite-sex preferences. As a result, the individual eventually begins to interpret experiences in that way. Positive encounters with opposite-sex individuals are forgotten, while negative experiences are focused upon in a way that gives undue influence and reinforces the perception of homosexuality. Likewise, negative experiences with same-sex individuals are discarded, while positive experiences receive out-of-proportion influence. Hence once someone has accepted the homosexual orientation, a self-fulfilling prophecy is incorporated and he or she perceives and interprets incoming information in the context of the same-sex orientation. Wilson refers to this as a filtering process and observes, "...stimuli which would suggest heterosexual tendencies are denied or filtered out" and secondly, "...most of the same-sex contact seems to get filtered in."35 In addition, Wilson maintains, "They are often shocked when they are helped through counseling to remember more clearly these experiences which have been filtered out."36


Homosexuality involves uncertainty when it comes to identifying the cause and it may be appropriate to talk in terms of "best guesses" for the causes, plural. There are several problems with accepting a totally "nature" argument. How do we know for sure biological or chemical differences determine sexual orientations as opposed to these differences coming as a result of and reflecting differences originating in the behavior? In other words, how do we know behavior is the result of biology rather than biology the result of behavior? Secondly, given a predisposition for the homosexual orientation coming from biology, should homosexual behavior be encouraged? For example, genetic links have been discovered for a predisposition to develop alcoholism in some people, yet we do not encourage these people to drink alcohol. Given biological roots, does that mean predetermination and under no control, or predisposition with possibilities to be comfortable with heterosexuality? Finally, if biological differences in homosexuals were shown, how can we be sure those same differences are not embedded within large proportions of heterosexuals? If we were able to analyze all heterosexuals would we actually find far more of those with the biological characteristics thought to be responsible for homosexuality actually among heterosexuals? Although there are legitimate questions, enough research evidence for innate differences between homosexuals and heterosexuals exists that it becomes difficult to say each and every homosexual learned the orientation completely as a result of nurturing and environment.

Dr. Gary Collins addresses the situation in this way: "Despite probably thousands of scientific studies, one conclusion seems clear: There is no clearly identified single cause of homosexuality." 37 In order to clarify the most accepted position, Collins discusses causality in terms of nature, critical period, and nurture. There may be prenatal influences which set up a homosexual predisposition, then in a critical or sensitive period during early development there are experiences which encourage the expression of the predisposition, and finally the family and social environment serve to reinforce the expression of predisposition. Collins continues, "We are left then with the conclusion that homosexuality can arise from a variety of causes. Some inconclusive data suggest that biological influences, operating before birth, may play some role in the development of later sexual orientation, but there is even greater evidence that homosexual preferences and behaviors are determined by psychological development and social learning."38

Meier, Minirth, Wichern, and Ratcliff end with this thought: "The best research to date, summarized by Jones and Workman (1989), indicates that often (but not always) prenatal hormones influence gender orientation. When combined with certain socialization experiences, homosexuality becomes more likely; however, such influences do not force an individual to engage in homosexual behavior." 39 They allow that predispositions set potential strengths and weaknesses, however socialization and choices combine with predispositions to influence a specific person. These authors delineate several likely causes which include: insecurity in sex-role identification, sexual experiences, behavioral conditioning from environmental conditions, and biological factors.40

Dr. Earl Wilson concludes:

First, there is a growing body of research which supports the idea that sex differentiation is predisposed before the child is born... Second, the degree to which prenatal dispositions can be altered is hotly debated... Third, there is evidence to support other causes of homosexuality... Finally, if, as the author contends, a high percentage of cases of homosexuality are best explained by social learning or parent-child explanations, then it would follow that there is much work for the counselor to do.41

Although we may never be certain of the origins of homosexual attraction and orientation, we must address homosexual behavior. Christians must be concerned on two levels: we must be willing to declare God's truth concerning homosexual behavior, yet we must have a servant's heart for ministering God's grace to homosexuals.


  1. "The Development of Sexual Orientation," The Harvard Medical School Mental Health Letter, February 1988, p. 4.
  2. Psychology, New York: Worth Publishers, 7992,367.
  3. Ibid., 368.
  4. "Homosexuality," The Harvard Medical School Mental Health Letter, February 1987, p. 6.
  5. "Does Homosexuality Have a Biological Basis?" The Harvard Mental Health Letter, June 1992, p.6.
  6. Chandler Burr, "Homosexuality and Biology:' The Atlantic Monthly, March 1993, p. 65.
  7. "Homosexuals in Boyhood," The Harvard Medical School Mental Health Letter, July 1989, p. 7.
  8. Chandler Burr, p. 62.
  9. The Knoxville News-Sentinel, August 1, 1992, p.A9.
  10. Ibid.
  11. "Is Homosexuality All in the Brain?" The Harvard Mental Health Letter, March 1992, p.7.
  12. Counseling and Homosexuality, (Waco, TX: Word, 1988), p. 69.
  13. Ibid., p. 70.
  14. Love is a Decision, Word Video Curriculum Resource, 1991.
  15. Chandler Burr, p. 59.
  16. Ibid., p. 60.
  17. Introduction to Psychology & Counseling, (Grand Rapids: Baker, 1991), p.272.
  18. Chandler Burr, p. 62.
  19. Counseling and Homosexuality, (Waco, TX: Word, 1988), p. 69.
  20. Ibid., p.72.
  21. Psychodynamic Therapy: Part III, The Harvard Mental Health Letter, December 1991, p.4.
  22. Gary Collins, Christian Counseling: A Comprehensive Guide, (Dallas: Word, 1988), p. 283.
  23. Psychodynamic Therapy: Part III, p. 4.
  24. Wilson, p. 57.
  25. Collins, p. 283.
  26. Wilson, p.57.
  27. Ibid., p.b8.
  28. Ibid., p. 60.
  29. Homosexuality, audiocassette #19, Christian Counselor's Library, (Waco, TX: Word Educational Products Division, 1980).
  30. Collins, p. 283.
  31. Changing Homosexuality in the MaIe, (New York: McGraw Hill, 1970).
  32. Collins, pp. 283-284.
  33. Ibid., p. 285.
  34. Wilson, p. 61.
  35. Ibid., p. 68.
  36. Ibid.
  37. Collins, p. 282.
  38. Ibid., p. 283.
  39. Ibid., p.272.
  40. Ibid., pp. 175-176.
  41. Ibid., pp.72-73.