Transgender activists frequently argue that men who wish to present themselves as women (male-to-female or MtF transgenders) have a female gender identity, probably innate, that conflicts with their biological sex. Such men, they argue, are “women trapped in men’s bodies” and therefore are suitable candidates for so-called “gender affirmation treatment”: drugs, hormones, and surgery that won’t change their sex but will help them imitate women in appearance. This argument has been deemed the “feminine essence narrative.”

Transgender activists offer this theory as scientific fact. But the feminine-essence narrative conflicts with another theory that enjoys much more evidentiary support, that explains a great deal of MtF gender dysphoria, and that offers hope for psychological treatment.

In the early 1990s, Dr. Ray Blanchard coined the term “autogynephilia” for the condition of a man who demonstrates a “propensity to be erotically aroused by the thought or image of himself as a woman.” Dr. Blanchard is the retired head of Clinical Sexology Services at the Centre for Addiction and Mental Health in Toronto, Canada. An internationally prominent clinician helping patients with various disorders related to gender identity and sexual orientation, and a contributor to the relevant sections of the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (the DSM-5), Blanchard has decades of experience in this area.

Autogynephilia is distinct from homosexuality; indeed, autogynephiles frequently interact sexually with real women and may present themselves as lesbians after they “transition” to imitation of the female sex. The distinguishing characteristic is the patient’s erotic attachment not to another person, whether male or female, but rather to an interior idea—the idea of himself as a woman. Among many case studies from his practice, Blanchard describes patients who are sexually excited by female bodily functions such as menstruation.

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This would seem to apply to Jonathan/Jessica Yaniv, a Canadian man—at various times claiming to be a woman—who muses about how to “bond” with young girls in restrooms or locker rooms by asking about tampons and other feminine-hygiene products. This is the same person who demands, under penalty of law, that female salon staffers wax his genitals, and who demonstrates a creepy obsession with female bodily functions.

More understanding of the condition can be gleaned from transgender/cross-dressing Twitter feeds. Male tweeters exchange giggly messages about their sexual fantasies, all of which feature themselves as women; debate the pros and cons of going bra-less; and discuss how to use hormones to simulate premenstrual syndrome, something biological women never do. They thrill to the idea of being among women—only women—and emulating their female essence. As feminist and lesbian commentator Lara Adams-Miller observes, this isn’t about gender identity; it’s about sexual fantasies, in which real women appear only as props.

Blanchard further explains that almost all adult MtF gender dysphoria results from, or is accompanied by, either autogynephilia or homosexuality. Either way, he draws this conclusion: “Transsexualism and milder forms of gender dysphoria are types of mental disorder, which may leave the individual with average or even above-average functioning in unrelated areas of life.”

Other clinicians agree with and have further explored Blanchard’s theories about MtF gender dysphoria. For example, psychology professor Dr. Michael Bailey of Northwestern University has written extensively about autogynephilia and its relationship to gender dysphoria, concluding that the evidence supporting Blanchard’s work greatly exceeds that for the feminine essence narrative.

But transgender activists will viciously attack anyone who suggests that gender-dysphoric individuals might not in fact have the brain of the opposite sex, or that they suffer from any type of disorder (see here and here). Twitter has boosted their efforts by blocking Blanchard’s expression of his clinical opinion as “hateful conduct.” Even though both Blanchard and Bailey believe that some adult patients may benefit from so-called “gender affirmation therapy” (GAT), perhaps even involving surgery, their position that gender dysphoria is often associated with autogynephilia disqualifies them from polite company in the radical crowd.

Why do transgender activists so strongly reject the concept of autogynephilia? Bailey suggests several possibilities. Gender-dysphoric individuals may fear that they will be denied “sex reassignment” if their motive is erotic satisfaction rather than deep-seated certainty that they are in fact women. They may be concerned that they will be considered sexually deviant. Or they may believe that the “feminine essence” narrative, even if unsubstantiated, will be more acceptable to the public and therefore smooth the path for other dysphoric individuals to be accepted for GAT.

Clinicians, too, may deny autogynephilia and accept instead the feminine essence narrative. As Bailey notes, they may hesitate to disbelieve their patients, who insist that they are females with female brains and are not simply erotically attracted to the idea of themselves as women. They may have “greater comfort with the idea of facilitating sex reassignment for reasons related to gender than to eroticism.” And they may also believe that “the feminine essence narrative may be beneficial for their patients’ psychological health and social interactions, even if it does not correspond to the true etiology of their desire for sex reassignment.”

Well, one might ask, so what? If a man would be happier imitating a woman, for whatever reason, why not play along (and, as GAT clinicians might note, make some money in the process)? For one thing, as Bailey points out, shutting down scientific inquiry via political pressure impedes the objective advancement of science. Further, denying the validity of the autogynephilia theory can harm gender-dysphoric patients by denying them access to therapies that could help them overcome their specific problems. “Homosexual and non-homosexual [autogynephilic] MtF transsexuals have different life issues and goals,” says Bailey, “and the persistence of the belief that they are similar prevents development of clinical interventions” that could benefit individual patients.

Bailey also argues that the hostility that is heaped on anyone who suggests the existence of autogynephilia—hostility that emanates, he believes, primarily from “autogynephiles in denial”—“makes it much less likely that [autogynephiles] can find resources that [could] help them understand themselves, forces them into the closet, invalidates their self-concepts, and heightens feelings of shame.” These men didn’t ask for this condition—its roots are deep and complex—but their situation can be improved through proper therapy. To accomplish that, however, society must recognize the condition for what it is, and offer actual help rather than knee-jerk affirmation that the painful longings of sufferers are perfectly normal.

Beyond allowing the development of better therapies for suffering patients, though, recognition of autogynephilia should guide society toward implementing appropriate policies. The condition illustrates an especially compelling reason (beyond the protection of the privacy and modesty of women) why biological men should not be allowed in women’s private spaces, such as restrooms or locker rooms. As demonstrated by the Yaniv case, not every MtF transsexual is a harmless individual who believes himself to be female and is therefore embarrassed to engage in highly personal behavior around men. Instead, he may be suffering from a condition that impels him to threaten women’s and girls’ privacy in ways even more dangerous than his mere presence.

As Adams-Miller concludes from perusing the Twitter feeds, autogynephiles “want to be on the ‘other side’ of the room, past the boundaries that separate men and women.” A society that allows—and even celebrates—the eradication of such boundaries is one that does not truly respect women.

To help individuals suffering from gender dysphoria, and to formulate best policies for dealing with the condition, we have to know what causes it. We need more information—not politically correct conclusions that defy scientific evidence. More importantly, we need a right understanding of what it means to be a healthy human being. Sacrificing women and girls to the erotic fantasies of individuals with mental illness should not be an option.