On the Science of Changing Sex

Latest Trans Taxonomy Study

Posted in Confirming Two Type Taxonomy by Kay Brown on January 21, 2019

critical-thinkingWondering if the latest science studies have proven Blanchard was wrong?  Surely by now they are finding Bailey was barking up the wrong tree?  That Lawrence has been debunked?

A study published just days ago, this year, 2019 looked to test the validity of the two type taxonomy by examining forty (N=40) transwomen before and after SRS at a clinic in Germany.  European researchers have for years preferred to classify the two types as “early” vs. “late” onset of gender dysphoria.  Most have used the age of puberty as the separation line under the (false) assumption that autogynephilic sexuality does not occur in pre-adolescents.  However in this study, they chose to use the age of legal majority, 18 years old, as the dividing line.

Given that many acknowledged autogynephiles state that their first experiences with erotic cross-dressing began in adolescence, this choice of age would seem to be misplaced.  However, in using statistics, any dividing line used to cut a single population into two that shows a significant difference between two groups is useful.

Consider a dividing line that is totally random and unlikely to have any correlation with putative differences between two populations (e.g. odd or even date of birth).  If that divisor is meaningless, even if there are two different populations, that random divisor will fail to sort them and the two populations will not appear to be different when measured.  They will have the same percentages of each population.  If however, even a poor divisor that has some, albeit, imperfect correlation, the two populations will be somewhat sorted and may show statistically strong differences when measured.  That difference is enough to show that there are in fact two different populations in the larger pool.  This is what Zavlin, et Al. have found.

I would not say that this study is perfect, given that we know that the age of onset of gender dysphoria is often misreported, and the authors fully acknowledge this.  Further, the authors didn’t even attempt to collect data on autogynephilia… and chose not to analyse their data using sexual orientation as the independent variable which has been repeatedly found to provide a stronger statistical signal.  Yet, in spite of these severe weaknesses and missed opportunities, their conclusion was still,

“Our study strengthens the theory that there are 2 distinct age-related subgroups within the MtF transgender population undergoing GAS.”

Specifically, the study, in agreement with earlier studies, found that “early onset” transwomen we more likely to be exclusively androphilic than “late onset” and to transition at a significantly younger age.  Put another way, exclusively androphilic transwomen are far more likely to report having experienced an early onset of gender dysphoria than non-exclusively androphilic.  Note there are twice as many non-androphilic subjects as androphilic.

N=40     Androphilic     Non-Androphilic
Early      10 (77%)             9 (33%)
Late         3 (23%)            18 (67%)

There are also very distinctive bimodal distributions in the self-reported age of onset and of age of obtaining surgery, strongly indicative of the two type taxonomy.  This finding is in agreement with an earlier study that also found a bimodal distribution of obtaining surgery.


What I found the most interesting, in agreement with my own experience and in talking to other transwomen, is that while the “late onset” group found psychotherapy to be nearly universally useful, “early onset” transwomen did not.  Interestingly, if we compare the data carefully, it supports the notion that androphilic transwomen did not find psychotherapy useful.   I’ve commented in other essays that psychotherapists mistakenly apply what is useful for autogynephiles to androphilic transwomen to negative effect (e.g. advising a highly gender atypical androphilic transkid to seek out opportunities to privately express her “feminine side” makes no sense, risibly so…).  Here we seem to have data confirming my anecdotal observations.

Further Reading:

Essay on Age of Onset vs. Sexual Orientation


Zavlin, D. et Al., “Age-Related Differences for Male-to-Female Transgender Patients Undergoing Gender-Affirming Surgery”, Journal of Pediatric Surgery (2019)


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