On the Science of Changing Sex


Posted in Transsexual Theory by Kay Brown on January 16, 2011

…on a hypothesis concerning bisexual  and asexual transsexuals.

androgynous faceIn the past, I’ve tried to keep from too much speculation, trying to describe and interpret the research into transsexuality.  But in this post, I wish to take a chance and speculate a bit, perhaps generate a hypothesis to test that speculation.

A bit of background:  Blanchard tested a hypothesis that there were only two types of transsexuals, rather than three or four as others had proposed.  The earlier researchers / commentators that had proposed that there were three basic types usually settled on Asexual, Homosexual, and Transvestite (Person and Oversey, Bentler, and even Green), though they didn’t always agree on the labels, nor on which group was the “real”  or “primary” transsexual.  Hirschfeld had used four types of people in general, not just for TS/TG folks;  Homosexual, Bisexual, Heterosexual, and Asexual.  Since this four grouping also would encompass the three grouping, it seemed prudent to start with four and see if there really were differences.  From this, Blanchard tested for autogynephilia and other characteristics, such as life arc (age of transition, level and quality of childhood gender atypicality, etc.).  From his study, he noted that three groups were very much alike in that the majority reported autogynephilia and had similar life arcs (statistically speaking) such as late transitioning, while one of the four was quite different, showing very, very low percentage reports of autogynephilia, greater childhood gender atypicality, and very early transitioning.  One group was “Homosexual” and the other was “Non-Homosexual”.  Thus, his data showed only two groups as being statistically separable, but with a non-statistically-significant (meaning, it could be noise in the sample) trend for the bisexual and asexual groups to report less transvestic autogynephilic individuals.  This was the state of things in the 1980’s and ’90s.

Then came the Nuttbrock study with many more subjects (N=571) in the late 2000’s.  The data exactly duplicated Blanchard’s study from twenty years previous.  And having enough subjects meant that the trend of having fewer bisexual and asexual individuals reporting transvestic autogynephilia (in this case, erotic arousal to cross-dressing) was shown to be statically valid, at least for bisexuals; There were so few (N=12) asexuals, that the trend might still be random noise, but when combined with Blanchard’s subjects, which reported about the same way, it gives us some additional confidence that it is real.  So, as I wrote earlier last year, we are now left with trying to generate new hypotheses to test that might explain this trend.

So, what is the trend?  Let’s use the Nuttbrock data:

Self-reported       Homosexual     Heterosexual    Bisexual   Asexual
Sexuality               (androphilic)   (gynephilic)
Number:                  (n=391)               (n=71)               (n=96)       (n=12)
Autogynephilia       23.0                     81.7                    67.7            66.7

And looking at age of transition:

Hormone Therapy      percentages                                              AGP
Adolescent(n=171) 91.8                 0.6                         7.6            14.0
Adult (n=242)           64.5               13.2                       22.2           42.6
None (n=158)            54.2               25.5                      20.2           59.5

And finally, we should add, from the Doorn study (N=31), that 85% of adult cross-dressers (TV/CD) reported erotic arousal to cross-dressing.  This number is vitally important, as it tells us the maximum number that will recognize and admit to such arousal.  Many researchers have looked into the issue of why less than 100% this group does report such arousal.  Those that don’t report ever having had such arousal, none-the-less report feeling the same exact type of satisfaction and most importantly, compulsive need, to cross-dress as those that do report such arousal… and in fact, the same type of feelings that those who found cross-dressing erotically arousing at one time, but no longer experience it as such.  For our purposes here, I think we can assume that they all experience autogynephilia in some form, in desire, if no longer such intense arousal.  That being so, we can note the amazing similarity to the percentage reporting AGP arousal found in the gynephilic transsexual group, who most resemble adult cross-dressers in life arc (up to but not including transition itself).

Here is where I am going to speculate, possibly rather wildly, but such is the nature of hypothesis generation.  If we assume that gynephilic transsexuals are all autogynephilic, and that we can take that 82% number as a baseline of how many autogynephilic transsexuals, regardless of self-reported sexuality, report that fact, we can use it as a means of making an estimate of how many autogynephilic transsexuals there are in a given sample:

Self-reported       Homosexual     Heterosexual    Bisexual   Asexual
Sexuality               (androphilic)   (gynephilic)
Number:                  (n=391)               (n=71)               (n=96)       (n=12)
Autogynephilia       28.0%                  100%                 82.7%         81.6%

And looking at percentage at age of transition again:

Hormone Therapy                                                                          AGP
Adolescent(n=171) 91.8                 0.6                         7.6            17.1
Adult (n=242)           64.5               13.2                       22.2           52.1
None (n=158)            54.2               25.5                      20.2           72.8

Note that we still have an interesting anomaly in that the estimated percentage of adolescent “early” transitioners is still significantly fewer autogynephilic individuals than would be predicted controlling for sexuality from the total study.  And, as expected, most of those who have not started HRT, would be autogynephilic.

So, if this estimation is correct, we are left with a question, why do fewer bisexual and asexual individuals report autogynephilia?  Several possible hypotheses come to mind:

1)  Fewer actual autogynphilic individuals who are bisexual and asexual recognize and admit to autogynephilia.

2)  Fewer self-reported bisexual and asexual individuals are autogynephilic (at least of the transvestic type).

3)  Some combination of the above two hypotheses will be found.

The safer bet is always to look at a combination of reasons, since real human lives are messy… but, if I had to take a guess regarding the bisexual group, I will go with more of the second hypothesis, as it fits with what we know of human sexuality in general, that many male-bodied people who self-report as bisexual do so because they honestly report that at sometime in their lives, they had some sexual experience(s) with women, but that their primary sexual orientation is androphilic.  If our estimate is correct, then 17.3% of the bisexual group is primarily androphilic.  I’d also bet that more of them transitioned at a younger age, than those who were autogynphilic (and experience pseudo-androphilia).  The asexual group is more of a question mark, but my guess would be the same, out of the twelve individuals in this study who report being asexual, two of them are primarily androphilic, but find their libido is low at the present time, or they are afraid of being emotionally hurt.

So, how do we test this hypothesis?

Addendum 1/22/2012:

I thought of a way to test this hypothesis using the reclassification from ‘homosexual’ to ‘non-homosexual’ that Lawrence performed on the Smith data set.  Originally, Smith et al. dichotomously sorted, by self-reported sexuality into “homosexual” and “heterosexual” (based on natal sex).  Lawrence then reviewed that original sort and resorted based on sexual history with natal females, as indicated by prior marriage to women.  That is, she looked at those who self-reported being exclusively androphilic and, in essence, assigned an implied assessment of being ‘bisexual’, based on their actual history combined with their stated sexual orientation.  She noted that the original ‘heterosexual’ and her resorted group had similar self-reported levels of autogynephilic arousal to cross-dressing.  However, when I look at the data, I note that though the are similar, they are not identical:

Percentage Reporting Cross-dressing Arousing
Self-Identified Heterosexual:  63%
Resorted Behavioral “Bisexual”: 52%

If we examine this as a ratio of Bisexual to Heterosexual self-report of autogynephilic arousal to cross-dressing we get 0.83.  The Nuttbrock ratio of Bisexual to Heterosexual self-reported arousal is 0.83.  They are identical!!!  Thus, this analysis supports the first, rather than the second, hypothesis, since in the Lawrence re-designated Bisexual group, we know that they are in fact non-HSTS because of their sexual history.  So, my original guess was wrong.  Nuttbrock’s Bisexual Group does not include etiologically homosexual transsexuals.

If the ratio of the two groups’ percentage reporting is the same, why aren’t the raw percentages?  Nuttbrock’s data was gathered in the open community, not in a clinical setting, as was the Smith data.  This may have led to more honesty, less social desirability bias.  The bias works equally on both self-reported heterosexual and bisexual groups, so that the ratio remains the same.

So why then do bisexual transsexuals report lower amounts of erotic arousal to cross-dressing?  Perhaps they experience other forms of autogynephilic arousal, as reported by Blanchard?  In any case, the Smith data set adds yet more evidence to the two type taxonomy, as already noted, but also adds to the observation that ‘bisexual’ transsexuals report slightly less arousal to cross-dressing than do ‘heterosexual’ transsexuals.

This area needs further research.

Addendum 1/23/2012

Lawrence resorted 23 out of 61 self-reported ‘homosexual’ transsexuals as not being exclusively so (23/61=38%).  If this percentage is similar, minus those who already sorted themselves as ‘bisexual’,  in the Nuttbrock data set, and that they reported erotic cross-dressing is the same percentage as Nuttbrock’s ‘bisexual’ group, then we can explain the reported figure of 23% of the androphilic group experiencing cross-dressing to be autogynephilically arousing.  That is to say, that about 33% of the “androphilic” group are not actually exclusively so.  Note that most of these started HRT as adults or are not on HRT.  This exercise reinforces the need for careful sorting based on actual sexual history, not simply by self-report.


A Further Assessment of Blanchard’s Typology of Homosexual versus Non-Homosexual or Autogynephilic Gender Dysphoria, Nuttbrock, et al. Archives of Sexual Behavior



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