Many religious and social conservatives believe that homosexuality is a mental illness caused exclusively by psychological or spiritual factors and that all homosexual persons could change their orientation if they simply tried hard enough. This view is widely pilloried (and rightly so) as both wrong on the facts and harmful in effect. But few who attack it are willing to acknowledge that today a wholly different, far more influential, and no less harmful set of falsehoods”each attributed to the findings of “science””dominates the research literature and political discourse.

We are told that homosexual persons are just as psychologically healthy as heterosexuals, that sexual orientation is biologically determined at birth, that sexual orientation cannot be changed and that the attempt to change it is necessarily harmful, that homosexual relationships are equivalent to heterosexual ones in all important characteristics, and that personal identity is properly and legitimately constituted around sexual orientation. These claims are as misguided as the ridiculed beliefs of some social conservatives, as they spring from distorted or incomplete representations of the best findings from the science of same-sex attraction.

Today we approach same-sex attraction with views grounded in social and biological scientific perspectives that are only partially supported by empirical findings. Until the early decades of the twentieth century, moral disapproval of “sodomy” guided public policy, but that grounding was displaced by a psychiatric model that viewed homosexuality as a mental illness. Once homosexuality came to be seen not as a sin but as a sickness, it became a simple matter for social science to overturn the opposition to homosexual acts. Alfred Kinsey’s studies of male and female sexuality, published in 1948 and 1953, portrayed homosexual behavior of various kinds as a normal and surprisingly common variant of human sexuality. In 1951, Clellan Ford and Frank Beach published Patterns of Sexual Behavior , their famous study of diverse forms of sexual behavior, including same-sex behavior, across human cultures and many animal species; they suggested a widely shared “basic capacity” for same-sex behavior.

But the decisive blow to the mental-illness construal of homosexuality came from a single study in 1957. Psychologist Evelyn Hooker published findings that convincingly demonstrated that homosexual persons do not necessarily manifest psychological maladjustment. On the basis of Hooker’s work, and the findings of similar studies, in 1973 the American Psychiatric Association amended its designation of homosexual orientation as a mental illness.

To avoid misunderstanding the phenomenon of homosexuality, we must grapple with the Achilles heel of research into the homosexual condition: the issue of sample representativeness. To make general characterizations such as “homosexuals are as emotionally healthy as heterosexuals,” scientists must have sampled representative members of the broader group. But representative samples of homosexual persons are difficult to gather, first, because homosexuality is a statistically uncommon phenomenon.

A recent research synthesis by Gary Gates of the Williams Institute, a think tank at UCLA Law School dedicated to sexual-orientation law and public policy, suggests that among adults in the United States, Canada, and Europe, 1.8 percent are bisexual men and women, 1.1 percent are gay men, and 0.6 percent are lesbians. This infrequency makes it hard to find participants for research studies, leading researchers to study easy-to-access groups of persons (such as visible participants in advocacy groups) who may not be representative of the broader homosexual population. Add to this the difficulty of defining homosexuality, of establishing boundaries of what constitutes homosexuality (with individuals coming in and out of the closet, and also shifting in their experience of same-sex identity and attraction), and of the shifting perceptions of the social desirability of embracing the identity label of gay or lesbian , and the difficulty of knowing when one is studying a truly representative sample of homosexual persons becomes clear.

With this caution in mind, we can now approach the broad beliefs shaping our culture. First, are homosexual persons as psychologically healthy as heterosexuals? Many believe so, and public representations of the scientific evidence support the belief. For instance, in 1986, in its amicus curiae brief for the Supreme Court case Bowers v. Hardwick , the American Psychological Association (APA) stated, erroneously, that “extensive psychological research conducted over almost three decades has conclusively established that homosexuality is not related to psychological adjustment or maladjustment.” Today, twenty-five years later, the association’s website still declares, after decades of research to the contrary, that “being gay is just as healthy as being straight.”

Evelyn Hooker, in her 1957 study, was careful to reject only the claim that homosexuality is always pathological. She never made the logically distinct assertion that homosexual persons on average are just as psychologically healthy as heterosexuals. It is well that she did not, because the consistent findings of the best, most representative research suggest the contrary, despite a few scattered compatible findings from smaller studies of less representative samples. One of the most exhaustive studies ever conducted, published in 2001 in the American Journal of Public Health and directed by researchers from Harvard Medical School, concludes that “homosexual orientation . . . is associated with a general elevation of risk for anxiety, mood, and substance-use disorders and for suicidal thoughts and plans.” Other and more recent studies have found similar correlations, including studies from the Netherlands, one of the most gay-affirming social contexts in the world. Depression and substance abuse are found to be on average 20 to 30 percent more prevalent among homosexual persons. Teens manifesting same-sex attraction report suicidal thoughts and attempts at double to triple the rate of other teens. Similar indicators of diminished physical health emerge in this literature.

Social stigma is the popular explanation, both in scientific studies and in mass media, for heightened psychological distress among homosexuals. The possibility that the orientation and all it entails cuts against a fundamental, gender-based given of the human condition, thus creating distress, is not raised. The correlation between social stigma and psychological problem is real, but the empirical case for the first causing the second has yet to be made. This has not stopped advocates, however, from battling alleged stigma by increasingly framing all “anti-gay sentiment” as a form of prejudice. This has led to the creation of new terminology: No matter how congruent with the scientific evidence, any belief that homosexuality is not a normal and positive variant of human sexuality is a manifestation of “homophobia” and “heterosexism,” a symptom of destructive “master narratives of normativity” (of which “heteronormativity” is a part).

Is homosexuality biologically determined at birth? A pervasive understanding is settling into Western culture that homosexual orientation, indeed any and all sexual orientations, has been proven by science to be a given of the human person and rooted in biology. Why does this falsehood”that homosexuality has been proven to have an exclusively biological cause”matter? It is the basis for asserting that sexual orientation is the same sort of characteristic as race or skin color, which has become, for instance, the foundational metaphor in the push for the right to marry someone of the same sex.

One reason it is generally believed that homosexuality is conclusively caused by biological factors is the supposed lack of a credible alternative. Two astonishing examples: The 2009 APA task force report on Sexual Orientation Change Efforts (SOCE), Appropriate Therapeutic Responses to Sexual Orientation , presents over and over as established “scientific fact” that “no empirical studies or peer-reviewed research supports theories attributing same-sex sexual orientation to family dysfunction or trauma.” Neuroscientist Simon LeVay, author of a major book on the science of same-sex attraction, in considering environmental and psychological factors influencing sexual orientation concludes that “there is no actual evidence to support any of those ideas.”

There are, in fact, many such studies and a lot of actual evidence. Recent studies show that familial, cultural, and other environmental factors contribute to same-sex attraction. Broken families, absent fathers, older mothers, and being born and living in urban settings all are associated with homosexual experience or attraction. Even that most despised of hypothesized causal contributors, childhood sexual abuse, has recently received significant empirical validation as a partial contributor from a sophisticated thirty-year longitudinal study published in the Archives of Sexual Behavior . Of course, these variables at most partially determine later homosexual experience, and most children who experienced any or all of these still grow up heterosexual, but the effects are nonetheless real.

To say that psychological and environmental variables play a part in causation does not mean that biology does not, rather just not to the extent that many gay-affirming scholars claim. The two most influential contemporary theories of biological causation focus respectively on fraternal birth order and genetics; each has some level of support, but for modest-sized causal effects at best.

The fraternal birth order theory hypothesizes that some mothers develop something akin to an allergic reaction to their body’s encounter with the male hormones generated by their male fetus, and hence manifest a hormonal resistance against the masculinization process in the developing male fetus. Males who were the product of such wombs are incompletely masculinized. And it is posited that the more male children such mothers bear, the more profound their reactions and the greater the likelihood that the later-born sons will be homosexual. In short, the more older brothers, the more likely the younger brothers are to be homosexual. The actual evidence such an immunological reaction exists is minimal apart from the raw claim that gay men tend to have disproportionate numbers of older brothers. But do they?

Early studies claiming to demonstrate a disproportionate presence of older brothers among homosexual men were based upon advertisement-recruited, volunteer samples vulnerable to volunteer bias. As Anthony Bogaert and Ray Blanchard, the major proponents of this theory, multiplied their reports of this phenomenon, their larger and larger samples were created by folding new volunteer samples into a common pool with their original samples, thus creating larger and larger nonrepresentative samples.

Recently, Bogaert analyzed two nationally representative samples and found only an exceptionally weak older-brother effect, but only for same-sex attraction, not for same-sex behavior. Then he analyzed an independent and truly representative sample eight times the size of his previous studies, finding no older-brother effect. At roughly the same time, a study of two million Danes and another of 10,000 American teenagers both failed to find the effect. It is thus mystifying why many gay-affirming researchers still confidently assert, like Simon LeVay, “that gay men do have significantly more older brothers, on average, than straight men.”

If there is a genetic component to sexual orientation, then the more two people share their genetic endowment, the more likely they are to share the same sexual orientation. The then-moribund genetic theory received a huge boost from J. Michael Bailey’s famous 1991 study that recruited subjects through advertisements and posted announcements throughout Chicago’s gay community. Bailey examined three groups in descending order of genetic similarity: genetically identical twins, fraternal twins and non-twin brothers who are essentially 50 percent identical, and adopted siblings who have no particular genetic similarity. Bailey reported a widely misinterpreted 52 percent “concordance” for identical male twins, compared with 22 percent for fraternal twins, 9 percent for non-twin brothers, and 11 percent for adopted brothers. The results generated wide and simplistic media coverage. It had been settled, the media suggested: Sexual orientation was determined by one’s genes. What was not widely understood was that only in 14 of the 41 identical-twin pairs did the two twin brothers match for sexual orientation; in the remaining 27 sets the identical twin brothers did not match.

But the deeper problem with the study was again one of sample representativeness. What if individuals were more likely to volunteer for the study if they shared same-sex attraction with a sibling, and less likely to do so if they didn’t? Using a more representative sample from the Australian Twin Registry, Bailey in 2000 saw the concordance for identical male twins fall from 52 to a mere 20 percent, and the matching for homosexual orientation between each pair of identical male twins fell to a mere 3 out of 27 pairs (11.1 percent). The findings of Bailey’s new study failed to reach statistical significance. The ballyhooed genetic effect had shrunk considerably, a fact that failed, of course, to capture any media attention and is often left out of the textbook treatments of the subject. In 2010, an impressive and much larger study utilizing the Swedish Twin Registry produced almost identical results: Among the 71 pairs of identical male twins of whom at least one twin was gay, in only seven cases (9.8 percent) was the second twin also gay, yet another statistically insignificant result.

But the search for a genetic mechanism continues, using a more statistically powerful calculation, that of heritability, which estimates how much of the variability of sexual orientation may be attributed to genetic influences. The higher this estimate, the greater the suggested genetic contribution. The best recent studies consistently generate heritability estimates for male homosexuality of 30 to 50 percent, a statistically significant finding that sounds quite powerful. Heritability estimates for female homosexuality are slightly less than for males, but still statistically significant. But what do heritability estimates of 30 to 50 percent mean?

Behavior genetics has established heritability estimates for a vast array of psychological traits. Quite a number of traits demonstrate much higher heritability than does homosexual orientation. Those with roughly similar heritability include social attitudes such as right-wing authoritarianism, inclination to religiosity, and church attendance. One study by a giant of behavioral genetics, Robert Plomin, found that the proclivity to watch television has an average heritability estimate of 45 percent, on par with the typical estimate for the heritability of male homosexuality.

Contrary to the assumptions of many social conservatives, biology does appear to play a modest part in determining sexual orientation. Contrary to the assumptions of many social progressives, psychological and environmental variables also appear to play at least a modest part in determining sexual orientation. In contrast to the hubris of those prone to making emphatic pronouncements, what we do not yet know about the causation of sexual orientation dwarfs the bit that we are beginning to know. And the fact that causation is indubitably a complex and mysterious by-product of the interaction of biological and psychological variables confounds the assertion that sexual orientation is just like skin color, determined at birth or even conception. And contrary to the suggestions of some, the involvement of some biological influence does not prove that change in sexual orientation is impossible. One of our foremost behavior genetics experts, Thomas Bouchard, has argued forcefully that “one of the most unfortunate misinterpretations of the heritability coefficient is that it provides an index of trait malleability (i.e., the higher the heritability the less modifiable the trait is through environmental intervention).”

If some measure of heritability does not establish that the trait is not modifiable, what does the direct evidence show about change? Attorney General Eric Holder, explaining the Obama administration’s decision not to defend the Defense of Marriage Act, repeatedly cited the “immutability” of sexual orientation: “A growing scientific consensus accepts that sexual orientation is a characteristic that is immutable.” The recent APA amicus brief for the Proposition 8 case is also forceful on the issue of change; contrary to claims that change is possible, they say, “research suggests the opposite.”

Has science established that sexual orientation cannot change? Dozens of scholarly papers appeared in journals from the 1940s to the early 1970s reporting that a substantial portion of those wanting to change homosexual orientation did change to some degree. But rarely since 1980 has a professional publication reported such results. Did science change direction and prove change impossible? Not quite.

Certainly, there has been lately less research of late studying the possibility of change. The removal in 1973 of homosexuality from the Diagnostic and Statistical Manual of Mental Disorders both changed the political environment in the mental-health professions and undermined grant funding for research on this subject. Many academics no longer had any motivation to study this phenomenon and considerable political reasons not to do so. Further, prior published research is commonly dismissed as inadequate. The APA’s website stated for many years that claims that homosexual orientation can change “are poorly documented. For example, treatment outcome is not followed and reported over time as would be the standard to test the validity of any mental health intervention.”

Such criticism took its most comprehensive form in the report of the 2009 APA task force studying SOCE (sexual-orientation change efforts). These scholars set extraordinary standards of methodological rigor for what they regarded as a reasonable scientific study of the possibility of sexual-orientation change, a move that resulted in the classification of only six studies out of dozens as meriting close examination. These studies were, in turn, dismissed for a variety of reasons, leaving the panel with no credible findings, by their standards, documenting the efficacy of SOCE. After dismissing SOCE for its lack of empirical validation, the panel then recommended gay-affirming therapy while explicitly acknowledging that it lacked the very type of empirical validation required of SOCE.

In the absence of evidence, it would be proper scientific procedure to acknowledge one’s ignorance. The members of the APA task force claim that their review has established that “enduring change to an individual’s sexual orientation is uncommon” and “that it is unlikely that individuals will be able to reduce same-sex attractions or increase other-sex sexual attractions through SOCE.” But even more-forceful claims have been made. The Public Affairs website of the APA for many years stated, “Can therapy change sexual orientation? No,” and insisted that homosexuality “is not changeable.” But has science proven this? Not at all; rather, skeptical reviewers have dismissed evidence of the possibility of change for some on the basis of such studies being methodologically inadequate by post hoc and artificially stringent standards.

Is sexual orientation immutable? With Mark Yarhouse of Regent University, I recently studied people seeking to change their sexual orientation. We assessed the sexual orientations and psychological distress levels of 98 individuals (72 men, 26 women) trying to change their sexual orientation through ministries organized under Exodus International, beginning early in the process and following them over six to seven years with five additional, independent assessments. Our original round of findings was published in a book titled Ex-Gays? ; the latest round, in the Journal of Sex and Marital Therapy.

Of the 61 subjects who completed the study, 23 percent reported success in the form of “conversion” to heterosexual orientation and functioning, while 30 percent reported they were able to live chastely and had disidentified themselves from homosexual orientation. On the other hand, 20 percent reported giving up and fully embracing homosexual identity, and the remaining 27 percent continued the process of attempted change with limited and unsatisfactory success. On average, statistically significant decreases in homosexual orientation were reported across the entire sample, while a smaller but still significant increase of heterosexual attraction was reported. The attempt to change orientation was not found to lead to increases in psychological distress on average; indeed, the study found several small significant improvements in psychological distress associated with the interventions. And lest we fall prey to the same mistakes we have been criticizing in others, we have said repeatedly that because our sample was not demonstrably representative of those seeking change among all religious homosexuals, these are likely optimistic outcome estimates.

I conclude that homosexual orientation is, contrary to the supposed consensus, sometimes mutable. “Homosexuality” is a multifaceted phenomenon; there are likely many homosexualities, with some perhaps more malleable than others. Not all interventions are the same; not all practitioners are equally skilled. Perhaps most important, those seeking change vary considerably in their intensity of motivation, in their resourcefulness, and in the context in which they try to change. Most of those seeking change and most of those who actually attain some level of change are highly religiously committed, and these individuals who believe in a God who intervenes in their lives are embedded in communities of care and are motivated by their core understanding of who they are as a person before God. It is a wonder that anyone without such resources successfully obtains sexual-orientation change.

Are homosexual relationships equivalent to heterosexual ones? In his ruling overturning Proposition 8, Judge Vaughn Walker cited UCLA psychologist Letitia Peplau’s testimony that “despite stereotypes suggesting gays and lesbians are unable to form stable relationships, same-sex couples are in fact indistinguishable from opposite-sex couples in terms of relationship quality and stability.” The APA’s brief for this case similarly claimed that “empirical research demonstrates that the psychological and social aspects of committed relationships between same-sex partners closely resemble those of heterosexual partnerships.” That brief relies upon the 2007 overview of research on same-sex relationships by Peplau and A. W. Fingerhut.

Here again we return to the issue of sample representativeness, which Peplau and Fingerhut handle with unfortunate evasiveness. They typically launch into discussions about various characteristics of homosexual couples without ever clearly stating that the studies they cite do not examine representative samples. They offer only intriguing hints that the studies on which they rely may be unrepresentative and hence potentially biased. They also raise in passing the provocative possibility that homosexual couples may bias their self-reports to look good.

Even so, intriguing hints of differences, of “nonequivalency,” between heterosexual and homosexual couples emerge from Peplau and Fingerhut’s survey. They mention one large study that found that 28 percent of lesbians had had sex outside their primary relationship”comparable to the 21 percent of women in relationships with men and 26 percent of men in relationships with women. By contrast, 82 percent of gay men had had sex with someone other than their main partner. However one construes such a striking difference in sexual monogamy, whether as a trivial stylistic difference or as indicative of something fundamental and pervasive, such a finding seriously challenges the equivalency hypothesis.

Stability is a relational characteristic of direct relevance to the types of functional concerns intrinsic, for instance, to evaluation for adoption fitness. How does equivalence look in this area? Peplau and Fingerhut cite one study that found that over a five-year period, 7 percent of married heterosexual couples broke up, compared with 14 percent of cohabiting male couples and 16 percent of cohabiting lesbian couples. They also summarize, without mentioning specific numbers, a more representative study from Norway and Sweden, which have sanctioned same-sex partnerships since the 1990s, reporting “that the rate of dissolution within five years of entering a legal union is higher among same-sex partnerships than among heterosexual marriages, with lesbian couples having the highest rates of dissolution.” Their rendering underplays the magnitude of the actual findings, which was that gay male relationships are 50 percent more likely to break up than heterosexual marriages, while lesbian relationships are 167 percent more likely to break up than heterosexual marriages. Odd that they would not mention these actual numbers.

One common obfuscation of such matters can be illustrated through the sensitive issue of rates of homosexual attraction among children raised in homosexual households. Summarizing this research, Gregory Herek, a psychologist who specializes in the study of homosexuality, wrote that “the vast majority of those children eventually grow up to be heterosexual.” It appears he is right, technically. Terms such as “a vast majority” are often used in this literature to obscure probabilistic trends in the data. The small bit of research that exists suggests increased rates of same-sex orientation among the children of such couples; my informal synthesis would be that gay parenting approximately triples or quadruples the rate of same-sex attraction. It may be technically true that “the vast majority of these children eventually grow up to be heterosexual,” but only because if being raised by same-sex parents increases the occurrence of same-sex attraction from 2 percent to 8 percent, 92 percent are still heterosexual. But a fourfold increase is still a sizable effect statistically.

Has empirical science established homosexual identity as positive and legitimate? Some would claim so. University of California psychologists Phillip Hammack and Eric Windell argue that a dramatic shift has “repositioned the scientific narrative of homosexuality from sickness to species ” and homosexuality is to be affirmed as “a legitimate minority identity akin to race and ethnicity.” The APA task force on SOCE declared in 2009 that “Same-sex sexual attractions, behavior, and orientations per se are normal and positive variants of human sexuality.”

Declarations that homosexuality is “normal,” “positive,” and “legitimate” would seem be the product of value judgments rather than objective science. The APA’s Proposition 8 brief argues that sexual orientation “encompasses an individual’s sense of personal and social identity based on those attractions, behaviors expressing them, and membership in a community of others who share them.” There indeed are persons who organize their lives around their sexual orientation. But to claim for all human persons that “sexual orientation encompasses an individual’s sense of personal and social identity” is remarkable both conceptually and scientifically. I cannot conceive of data comprehensive enough to support this claim. And how does science establish that such a grounding of human identity is “positive”?

Science may be able to contribute valuable evidence about the association of such identities with certain measurable functional realities of life, such as whether such individuals experience heightened levels of emotional distress, report levels of self-esteem comparable to those of others, and so forth. But how did science become the arbiter of what is positive? Such a thing can happen, precisely as Hammack and Windell suggest, through a paradigm shift within the discipline, a decision of practicing psychologists to embrace the “minority narrative of homosexuality.” But can empirical science establish homosexual orientation as “a legitimate minority identity” or sexual orientation as a fundamental for constituting the self? I hardly see how.

The APA SOCE task force, and the gay-affirming psychological mainstream it represents, describes gay-affirming therapy as pursuing “congruence” between identity and sexual orientation. It seems to take this as a self-evident good. But the task force also seems to recognize that an affirmation of same-sex attraction goes beyond the traditional competence of science. Reflecting on the clash of scientific and religious perspectives on this point, they note that “some religions give priority to telic congruence while, in contrast, “affirmative and multicultural models of LGB psychology give priority to organismic congruence. ” In a moment of exceptional clarity, the task force put its finger on a core issue: Gay-affirming psychologies necessarily embody extrascientific moral and ethical deliberations that raise the potential of conflict with religious beliefs, precisely because the very act of giving priority to organismic congruence is a religious and ethical choice.

As the late theologian Don Browning noted, psychology “cannot avoid a metaphysical and ethical horizon.” Meaningful consideration of the nature of personhood always involves moving beyond the analysis of human life to the broader valuation of this or that characteristic, this or that phenomenon, this or that outcome. The social sciences do not contain within themselves adequate resources to adjudicate among conflicting ways of understanding the good. Individual scientists, stepping beyond their professional bounds, may declare homosexual orientation positive, normal, and legitimate, but such science cannot make this judgment. Such judgments are the domain of religion, theology, and philosophy. The twin claims that science conclusively establishes that sexual orientation grounds human identity and that psychology as a science establishes the legitimacy of such a claim are too far a reach.

So where does this leave us? We know much more now than we did ten and thirty years ago about the emotional well-being of homosexual persons, the complicated interaction of nature and nurture in the causation of sexual orientation, of the complicated and difficult possibilities of sexual-orientation malleability, of the functional and descriptive characteristics manifest in same-sex partnerships, and of the contours of the psychological identities of homosexual persons. The contributions of science to this area, however, remain sketchy, limited, and puzzling. It is remarkable how little scientific humility is in evidence given the primitive nature of our knowledge.

Nevertheless, our culture is polarized between those relentlessly advancing the full acceptance and normalization of homosexuality, indeed of all sexual variations, and those resisting those moves. As religious believers, we must confess our own culpability in creating the mess we are in.

We were complicit, even if ignorantly and passively so, in the cultural embrace of the disease conceptualization of homosexuality. We off-loaded responsibility for the articulation of a thoughtful, caring, theologically rich, and pastorally sensitive understanding of sexual brokenness grounded in our various religious traditions by conceptualizing homosexuality as a disease, and so we were unprepared for the vacuum created by that explanation’s timely demise. The best ecclesiastical, professional, legal, and social policy will be founded not on falsehoods or grotesque and indefensible simplifications but on a clearheaded grasp of reality in all its complexities, as well as on a humble recognition of all that we do not know.

Stanton L. Jones is provost and professor of psychology at Wheaton College. An expanded version of this essay is available at www.christianethics.org , as is a document offering the specific citations for this February, 2012, feature article.