FAQ on the Science
This FAQ is on the science of transsexuality. For the FAQ on the sociology of transsexuality, please visit www.transkids.us FAQ
How many types of transsexuals are there?
Short answer: Two for each natal sex.
Full answer: There are two basic etiologies (causes / conditions) that are found in transsexuals.
One, often thought of as the “classic” pattern, is extremely gender atypical from early childhood, often gender dysphoric from school age onward, and universally attracted to their same natal sex. Transsexuals with this etiology are most often called, “homosexual transsexuals” (HSTS) in the scientific literature.
There are some differences in life arcs of Female-to-Male (FtM) HSTS and Male-To-Female (MTF) HSTS. The median age of transition for MTF of this type is 20 years old, with a range of early puberty to mid 20′s. More than 90% transition before the age of 25 and it is nearly unheard of to find one who transitions after age 30. The median age of transition for FtMs is a slightly older, with a moderate number transitioning in their 30′s and later.
The other type is generally gender typical in behavior as a child, but may experience gender dysphoria, none the less, usually kept secret, due to correctly understanding that this is socially undesirable. They are mostly attracted to the opposite natal sex, but may be behaviorally bisexual or asexual. They exhibit an unusual sexual arousal pattern in which they find the thought of being or becoming the opposite sex to be arousing. They may also find altering their appearance to approximate the opposite sex, by cross-dressing, to also be sexually arousing. In Female-to-Male (FtM) transsexuals, it is called “autoandrophilia” (AAP) and in Male-To-Female (MTF) transsexuals this arousal pattern is called “autogynephilia” (AGP). Transsexuals with this etiology are most often called, “non-homosexual transsexuals” in the scientific literature.
Before transition, the natural behavior of these MTF transsexuals is gender typical, easily passing as typical straight men, often marrying women, fathering children, and successful in stereotypically masculine careers. The mean age for transition is 35 to 40 years old, with a range of early 20′s to very old age. They are far more likely to transition in individualistic cultures than socially interdependent cultures.
Because of the difference in mean age at transition, the first type is often called, “early” or “young transitioner” and the second type “late transitioner”. However, the range of age at transition of the two types overlaps and this nomenclature may thus be misleading, especially for a “late transitioner” who transitions “early”. It is important to remember that the key difference between the two is that the first type is exclusively, or primarily, “homosexual” with regard to natal sex and gender atypical in natural behavior and manner, making it difficult to fit in as their natal sex, while the second type is defined by their atypical sexuality, being aroused by the thought of being or becoming the opposite sex.
In the FtM population, the first type (HSTS) is by far the most common, the second being quite rare. For more information see my essay on FtM androphilia.
In the MTF population in Western (Northern European derived) societies, the incidence rate is reversed, with the second type (non-HSTS) being the majority. In many other parts of the world, the first type predominates.
For more information, read most of this blog 
.
How do scientists know that there are two and only two types of MTF transsexual?
Short answer: Statistics
Full answer: Studies, going back to the 1970′s, looking at the correlation between sexual orientation, age of transition, childhood gender atypicality, and autogynephilia consistently find two statistically significant groupings.
One group is primarily attracted to men, transitions quite young, were noted to be feminine (sissy boys) by parents and teachers, and were unlikely to report finding wearing women’s clothing to be sexually arousing (less than 15%).
The other grouping was sexually attracted to women, as evidenced by extensive sexual experience with women, but may identify as bisexual or asexual, transitioned later in life, were considered to have been typical boys by their parents and teachers, and were very likely to report finding wearing women’s clothes to be, or once had been, sexually arousing (85%). No other groupings had such strong statistical signals.
When using statistics with people, one always expects “noise”. People misunderstand the questions, prefer not to provide definite answers, wish to appear to better advantage, or simply like to introduce bogus answers to cause mischief… so the statistics can never be 0% vs. 100% in any study; but 15% vs. 85% is a very, very strong statistical signal in psychology studies.
This is not the only statistic that shows that there are two and only two types.
For more information click on the category Confirming Two Type Taxonomy.
Aren’t “Early” and “Late” transitioning transsexuals the same, but just transitioned at different ages?
Short answer: Only for autogynephilic transsexuals.
Full answer: The two types (HSTS vs. non-HSTS) are not defined by their age at transition, and can both transition “early”, say 20 years old. They are still very different in clinical presentation: sexual orientation, level of autogynephilia, natural gendered mannerisms, etc. Age of transition and age of first awareness of gender dysphoria are not the key clinical differences since the two types have distinctly different etiologies and motivations. Autogynephilic transsexuals can potentially transition at any age, from teenager to old age, but the average age is 35.
However, there is no such thing as a “Late” transitioning Homosexual Transsexual (HSTS), since the average age is 20 years old. That is to say, that by age 20, half have already transitioned. Nearly all will have transitioned by age 25 and it is unheard of to transition after age 30. If a potentially HSTS individual is over 25 years old, they are extremely unlikely to transition. Such an individual will simply continue to live as a gay man.
Personally, of the many dozens I’ve met and conversed with, and many more I’ve known of, the oldest MTF HSTS transition age that I’ve known of was 23 years old.
What is autogynephilia?
Short answer: The propensity for some natal males to find the thought of becoming or being feminine/female to be sexually arousing.
Full answer: The word comes from “auto”, meaning ‘self’, “gyne”, meaning ‘female’, and “philia” meaning ‘love’. In other words, the “love of oneself as a woman”. It can take many forms, from being aroused by temporarily simulating the appearance of a woman, that is cross-dressing in clothing that is culturally prescribed for women only, to living as a woman in society, full time, to “changing sex”. Over time, the overt level of sexual arousal may diminish, but the “love” of being feminine/female remains.
For more information see my essay Autogynephilia
Does a “female gender identity” or “gender dysphoria” cause autogynephilia?
Short answer: No.
Full answer: Not all autogynephilic males identify as women. Even in those who later transition, female self-identification often occurs years after intense erotic cross-dressing or other autogynephilic ideation surfaces in childhood or adolescence. The histories of AGP transsexuals strongly suggests that autogynephilia causes gender dysphoria and subsequent female self-identification, not the other way around.
For more information, see my essay on The Origins of Cross-Gender Identity in Transsexuals.
Aren’t natal female women also autogynephilic?
Short answer: No.
Full answer: While it may be comforting to autogynephilic individuals to imagine that their very unusual and intense sexuality is the same as, or at least similar to, natal women, it is not. Most women are sexually attracted to their sexual partners. They are aroused by sexual ideation in which their partner is the significant figure, not themselves, their own appearance, nor their mode of dress, which, if present, is of a supporting, rather than leading role.
Although there is a single paper, by C. Moser, which purported to have found autogynephilia in women, it in fact did not. The test instrument (questionnaire) he devised was cleverly written to obtain positive answers to ambiguous questions that only superficially resembled questions used in instruments that are only valid for gender dysphoric males. For example, one question asked if one fantasized about having a “sexier” body? (One would hardly expect that women would fantasize about having an uglier one!) Another question asked about becoming aroused while preparing for a sexual encounter with a lover. (Such arousal would arise due to anticipation, not the mere fact of getting dressed in womens’ clothing!)
Thus, the paper is of no scientific value in exploring the nature of womens’ sexuality.
For more information about this study, see my essay on the lack of validity of Moser’s paper.
Aren’t some exclusively androphilic MTF transsexuals also autogynephilic?
Short answer: No.
Full answer: Research has shown that autogynephilia only occurs in the presence of gynephilia. Exclusively androphilic transsexuals don’t have autogynephilia because they aren’t gynephilic.
Using questionnaires and single item questions regarding sexual orientation of transsexuals only statistically separates etiologically exclusively homosexual transsexuals from non-homosexual transsexuals. The confusion occurs largely because of the phenomena of pseudo-androphilic autogynephilia, in which an individual’s behavioral autogynephilic sexual ideation includes sexual acts, as a female, of sex with men, show up in the studies in the “androphilic” study group. But such individuals are not originally, nor predominantly attracted to men; their attraction is to taking the female role in sex with men. Scientists, using statistics, can accept and account for this as “noise” in the signal. One can reduce the number of such individuals by using interviews to obtain more of the actual sexual history, most particularly, their history of sexual experiences with women. The simplest indicator is their history of marriage to women, as gynephilia, attraction to women, is the single most likely motivator to marry a woman.
For more information, see my essay on Pseudo-Androphilia.
Aren’t there exclusively gynephilic MTF transsexuals that aren’t autogynephilic?
Short answer: No.
Full Answer: Although studies nearly all indicate that only 85% of exclusively gynephilically identified transsexuals report that they experienced autogynephilic arousal to cross-dressing, this isn’t the only form of autogynephilia. Further, even studies of self-identified transvestite / Cross Dressing (TV/CD) men show that only 85% report such arousal. One study showed that gynephilic cross-dressers who stated that they did not experience sexual arousal to cross-dressing, did in fact have measurable penile erections when listening to cross-dressing stories. So, it appears that 85% is the maximum percentage of individuals from either group that will recognize and admit to such arousal, even though it has been demonstrated that they do experience such arousal. This is likely to be the result of Social Desirability Bias in responding to the question in both groups. For many, in a sex negative / ‘phobic society, to admit to such arousal would be admitting to a very negative personal trait. This applies even more so today for transsexuals, given the negative position such admission puts them into with regards to other transsexuals (who are themselves likely to be autogynephilic) who stigmatize those who publically admit to being autogynephilic.
For more information see my essay on Social Desirability Bias in transsexuals.
What causes autogynephilia?
Short answer: We don’t know.
Full answer: Seriously, we don’t know. But we do know what doesn’t cause autogynephilia. It is not caused by being forced to wear girls clothes as a child or teen (though that is a common autogynephilic sexual fantasy). It isn’t associated with being gender atypical as a child. (Most autogynephilic males were considered to be very typical boys growing up, by parents and teachers.) It isn’t caused by an overly smothering mother or distant father, or a defense mechanism against Oedipal conflicts (debunked psychodynamic formulations by Freudian pseudo-scientists).
Our best guess is that it is a form of Erotic Target Location Error, in which the erotic target, femininity / femaleness, is sought on / within oneself, rather than sought after in other people. There are hints that part of the brain responsible for seeking out the erotic target in the environment is somehow different, likely from birth, in people with Erotic Target Locations Errors. These brain differences appear to be inheritable, and thus not of psychogenic origin. The inheritable factor can effect both natal male and female siblings, but is far more likely to effect natal male children.
For more information see my essay on Erotic Target Location Errors
What is Gynandromorphophilia?
Short answer: Sexual and affectional attraction to MTF transsexuals, especially pre-operative.
Full answer: The word comes from “gyne”, meaning “female”; “andro”, meaning “male”; “morpho meaning “body shape”, and “philia”, meaning “love”. Thus the word means the “love of males with a female body shape”. Thus, this is the sexual attraction to MTF transsexuals, most especially pre-operative transsexuals.
It is well recognized that autogynephilic individuals, both AGP transsexuals, and transvestites/cross-dressers, are also likely to be gynandromorphophilic. However, not all gynandromorphophilic individuals are autogynephilic. Such individuals are most likely male, as gynandromorphophilia is commonly found alongside simple gynephilia, and men are more likely to be gynephilic than women. But some women who are primarily androphilic occasionally also experience gynandromorphilia if they are attracted to feminine behaving males (e.g. ‘fag hag’ as well as ‘transfan’).
For more information see my essay on Gynandromorphophilia.
Are MTF transsexuals taller or shorter than non-transsexuals?
Short answer: It’s complicated.
Full answer: Non-homosexual (AGP) transsexuals are, as a group, exactly average height compared to non-transsexual men, as a group. But since in everyday situations we usually compare transwomen to non-transsexual women, not men, they seem far, far taller than average, as a group.
However, many clinical observers have noted that HSTS transkids are shorter and slighter than non-transsexual men, but taller and huskier, than non-transsexual women. One Canadian study tested this observation and found very robust evidence that this was true. But another study in a Netherlands clinic failed to replicate the finding. So, at the present time, we are still waiting for answers. (From personal observation in the USA, I do believe it is true, MTF HSTS are indeed shorter than AGP transsexuals, as a group.)
For more information see my essay Searching High and Low
Do FtM transsexuals have “male brains”?
Short answer: Sort of.
Full answer: MRI imaging suggests that the majority of FtM transsexuals have masculinized brains, likely due to organizational effects of androgens in utero. However, they are not fully masculinized until they begin testosterone, since there are activational effects of HRT.
Do MTF Transsexuals have “female brains”?
Short answer: It’s complicated.
Full answer: The evidence for feminine, exclusively androphilic transsexuals is that they share with conventionally homosexual men certain neurologically feminized features, since birth. In transsexuals, these features are likely to have been more feminized than those found in conventionally homosexual men. These features are believed likely to have been influenced by a lack of androgens (“male” hormones) in utero at specific times in the development process. There have also been suggestions that a genetic or epigenetic difference in the genes that code for androgen receptors may also play a role. The extent of such feminization is likely to vary from individual to individual, so it is unlikely that most exclusively androphilic transsexuals are completely femininized, though a few may be close.
In AGP transsexuals, there is no evidence that they have feminized brains, quite the contrary. But, there are two independent papers that suggests that autogynephilic transsexuals have several neurological features, (e.g. high levels of grey matter in the right putamen) that is different than both men and women before beginning hormone replacement therapy. We simply don’t know what these differences mean yet.
However, there is strong evidence that taking female hormones alters other neurological features (e.g. BSTc) toward the feminine morphology. This is likely due to the absence of androgens, as castrated men show the same shift. Thus, both types have more feminized brains, due to taking hormones, than non-transsexual males. Thus, one could say, with all honesty, that after years of taking female hormones, anti-androgens, and SRS, that AGP transsexuals do, in a certain sense and limited extent, have “female like” brains.
For more information, select the blog category, Brain Sex.
Didn’t a study find that the BSTc proved that all MTF transsexuals have female brains?
Short answer: No.
Full answer: For a short while, many thought that the BSTc, a sexually dimorphic feature in the brain, was female-like in older transitioning transsexuals. This would only have been interesting if it had been that way since birth, or at least since before HRT. However, it was later found, by the very same researchers, that the BSTc was only sexually dimorphic after puberty, that the amount and time of exposure to testosterone as teenager and adult, changed the size of the BSTc. Hormone Replacement Therapy (HRT) was entirely responsible for the change in BSTc found in transsexuals, as HRT and SRS reduces the size and neuron count of the BSTc and other features.
For more information, select the blog category, Brain Sex.
Does transsexuality run in families?
Short answer: Yes.
Full answer: The two types do tend to run in families, but not the same families. That is, autogynephilia (and autoandrophilia) tend to run in a given family while feminine androphilic transsexuality and conventional male homosexuality tend to be found in their own families. The likelihood that an exclusively androphilic MTF transsexual will have an exclusively androphilic MTF transsexual sister or homosexual brother is higher than expected by random chance. While it is also been noted that father and son often share an erotic cross-dressing habit. There is even a famous FtM transsexual, who is primarily androphilic (identifies as a gay man) and (in my own opinion) is strongly autoandrophilic, who has an autogynephilic MTF transsexual sister. But, I know of only one case history where the two types have been found in the same family.
For more information see my essay on transsexual consanguinity.
Does taking cross-sex hormones change one’s sexual orientation?
Short answer: No.
Full Answer: If hormones taken in adulthood changed one’s sexual orientation, it would have been used to “treat” homosexuals to make them stop being homosexual. This was tried, and found not to work, in either direction. One’s sexual orientation is not effected by HRT (Hormone Replacement Therapy).
However, HRT can affect the libido, the level of sexual appetite, as well as aggressiveness and risk taking. For FtM transmen, taking testosterone often increases one’s libido dramatically. For MTF transwomen, taking anti-androgens can reduce libido. There is both anecdotal and limited statistical data indicating that HSTS and AGP transwomen experience different levels of libido changes when initiating HRT, with AGPs experiencing a greater drop. This may be mediated by differences in the level of sex hormone organizational effects upon the brain in utero, in which AGPs develop greater sensitivity to levels of testosterone. In addition, the type of HRT can affect libido post-operatively. Anecdotal evidence suggests that estradiol increases libido in HSTS, but not AGP transwomen, when compared to conjugated estrogens (Premarin) and estinyl estradiol. Additionally, bio-identical progesterone (micronized) seems to have less libido reducing effects, and may even increase libido, in HSTS, while medroxyprogesterone (progestin) reduces libido in both AGP and HSTS.
Again, none of these HRT protocols affect one’s sexual orientation, only one’s libido. Because autogynephilia is a form of sexual orientation, HRT can affect the level of overt autogynephilic arousal in AGP transsexuals.
For more information see my essay on testosterone’s affect on autogynephilic arousal.
While, a number of MTF AGP transsexuals have reported that their perceived sexual orientation changed after transition, it has been shown that this is because of autogynephilic pseudo-androphilia, in which an individual’s behavioral autogynephilic sexual ideation includes sexual acts, as a female, of sex with men. Since such autogynephilic ideation depends upon being anatomically female, or at least dressed as female, such perceived orientation changes occur as a consequence of being able to actualize the fantasy during transition or post-operatively.
For more information, see my essay on Pseudo-Androphilia.
Does HRT change sex pheromones?
Short answer: No.
Full answer: You may have seen advertisements for human sex pheromones in the back of popular magazines; These claims are fraudulent. Although it is true that HRT will cause changes to body and urine odors, sometimes dramatic changes, these are not pheromones. Humans don’t use pheromones.
For more information, see my essay on Pheromones.
What is the average intelligence (IQ) of MTF transsexuals?
Short answer: It’s complicated.
Full answer: For exclusively androphilic transsexuals (HSTS), the data suggests that they have, on average, the same IQ spread as is found in the general population: Average IQ=100 That is to say, that one will find the same number of dull witted as bright individuals, with most just being average.
For AGP transsexuals, the data from one study showed that they are typically well above average IQ=121.7 This is likely because of a socio-economic selection pressure such that only those non-HSTS / Autogynephilic gender dysphoric individuals who feel that they can “afford” to transition, follow through and do. Further, such AGP transsexuals are more likely to transition in societies that are individualistically oriented, as opposed to interdependent. That is to say, that AGP individuals transition more often when they are already socially and financially successful and living in a society that grants more social latitude to such successful individuals. Highly intelligent individuals living in individualist societies tend to rise to the top, where, if they are gender dysphoric, have greater socio-economic status that allows them to successfully transition.
For more information see my posts on Societal Individualism and Intelligence
What is the average intelligence (IQ) of gay people?
Short answer: The same as straight people.
Full answer: Although this question is not about transsexuals, we get asked this question quite often. The fact that this question keeps getting asked suggests that there is much ignorance about human sexuality. For the record: Gay people, both men and women, have exactly the same average and range of intelligence as straight people, period.
