On the Science of Changing Sex

The Age of Innocence

Posted in Female-to-Male, Transgender Youth, Transsexual Field Studies by Kay Brown on February 28, 2011

At what age should transkids start HRT?

OH, if you were a little boy,
.  And I was a little girl –
Why you would have some whiskers grow,
.  And then my hair would curl.
Ah! if I could have whiskers grow,
.  I’d let you have my curls;
But what’s the use of wishing it –
.  Boys never can be girls.
–Kate Greenaway, Marrigold Garden, (1885)

For physicians and other health care providers, an over-riding concern is to “do no harm”.  One of the fears for such care providers is that of starting a course of treatment intended to treat a condition, only to discover that they misdiagnosed the patient and gave a treatment that not only was unneeded, but potentially harmful.

In the case of trankids, both MTF and FtM, the sooner one can begin hormonal & surgical treatment and social support interventions to allow them to successfully transition into the appropriate gender/sex role so as to take advantage of the normal adolescent physical and social maturation process along side their peers, the better the long term outcome.

But, as the very recent Steensma study, as well as many before it, shows, not all gender atypical children will be gender dysphoric, and not all gender dysphoric children will persist as such into their teen years.  Thus, the study was conducted in the hope of finding differences between persistors and desistors, so that clinical treatment decisions can be made as early as possible.  The earlier one can separate the two, the earlier one can begin to treat the transkids, while letting non-transsexual teens grow up naturally, without potentially harmful iatrogenic trauma.

Because healthcare providers have not been able to accurately predict which gender atypical / dysphoric children will persist, a number of practitioners have begun recommending and using a puberty blocking protocol, under a harm reduction model in which the persistors are protected from the harmful effects of their endogenous hormones, while refraining from iatrogenic injury from exogenous cross-sex hormones in those who will desist from their earlier gender dysphoria.  The current recommendation is that such puberty blockers be used until the individual is 16 or even 18 years old, at which time, if he/she is still a persistor, they may be switched to cross-sex hormones, while the desistors may terminate the puberty blocking protocol at any time.  (There is a built in bias for desistors and against persistors in that desistors can begin a prefered hormonal protocol, simply by stopping the puberty blockers, but persistors must wait and “prove” to healthcare workers that they are ready.)

The problem with this protocol is two fold.  First, it is not without its own potential for iatrogenic harm in that delaying puberty reduces the eventual strength of the bones in adulthood.  This may not be immediately harmful, but those children will someday be older adults, whose bones will be more prone to breaks.  Second, for MTF transkids, delaying puberty means that they will continue to grow taller, potentially reducing their ability to pass successfully as female.  This effect may however be welcomed by the FtM transkids, but their desisting female peers may not feel the same.

Another problem with this protocol is that it is very expensive, far more expensive than cross-sex Hormone Replacement Therapy (HRT). For those who live in countries who do not have a generous state provided health plan, this may be a deal breaker.

So, for health care providers and parents alike, it may be better if they can accurately predict who will desist and who will persist.  Getting this data is the object the Steensma study.  The Steensma study is short on statistics, but what they do have is remarkable:

.                                Total group       Persisters     Desisters
.                                    (N = 53)            (N = 29)       (N = 24)

Natal sex
% (N) Boys             56.6 (30)          58.6 (17)      54.2 (13)
% (N) Girls              43.4 (23)          41.4 (12)       45.8 (11)
Age at childhood
M (SD)                   9.41 (1.46)*     9.92 (1.26)    8.81 (1.47)
Age at follow-up
M (SD)                 16.11 (1.70)     16.14 (1.84)   16.07 (1.54)
Full-scale IQ
M (SD)            100.26 (12.82)    98.83 (12.28)  102 (13.50)

* Significant difference observed between persisters and desisters in age at childhood assessment (t(51) = 2.968, p < .05), Cohens d = 0.81 .

For starters, the IQ of the persistors is 98.83, essentially average.  Although this is combining FtM and MTF, the number agrees with my earlier estimate of 98.6 for the MTF HSTS population.

But, the more important data is that there is a difference between the ages of childhood assessment, the age at which their parents brought them to a clinic for evaluation.  (The difference being on average a little over a year, or over 10% of their age, and a very large effect size of d = 0.81 )  But, the study makes it very clear that there was very little difference between the two groups in their early childhood gender atypicality at presentation.  So why is there this difference?  Why would the parents of persistors wait longer than those of desistors?

Because they don’t!  It wasn’t that parents of persistors waited longer, it was that many desistors, desisted at an earlier age, such that their parents never brought their children in for assessement.  As they get older, fewer and fewer parents of desistors would bring in their children.  But, the persistors would continue to be brought in at later and later ages.  Indeed, the authors specifically stated that from the interviews, the desistors clearly articulated that from age 10 to 13 were critical for their change in gender dysphoric feelings.  While, for persistors, that same age only confirmed and strengthened their feelings.  Thus, both interview report and the statistics agree that something special seems to be happening starting at around the age of ten or even a little younger.

Starting around the age of 10, and for the subsequent years, the persisters indicated that their crossgender preferences and behaviour and their gender identity remained stable, but that their dysphoric feelings intensified. The intensification of gender dysphoria was attributed to three factors; (1) Certain changes in their social environment, (2) The anticipation of and/or actual physical changes during puberty, (3) The first experiences of falling in love and discovering their sexual orientation.

The authors, in focusing on what the teenagers said were influential, may have missed a critical factor.  What’s so special about the age of ten?  This is well before puberty.  The authors focused on changing social factors, but could it be that biology is the important factor?  McClintock and Herdt point out that sexual attraction is first noted well before our classic definition of puberty, that of the maturation of the gonads and subsequent increase in testosterone, estrogen and progesterone.  Instead, other hormones start earlier, typically around ten years old with Adrenarche.  And this is the age at which one’s sexuality begins to be recognizable.

So what’s so special about adrenarche?  As the Wikipeadia page (linked above) explains it, “Unlike the physical changes that occur during puberty, adrenarche is primarily an emotional and psychological stage of development.”

And so, as their sexuality becomes visible,

With regard to sexual attraction, all persisters reported feeling exclusively attracted to persons of the same natal sex, which confirmed their gender identity as they viewed this attraction as a heterosexual attraction. They did not consider themselves homosexual or lesbian.

For the desisting boys, some came to recognize that they were gay or bisexual, essentially confirming the results of many other studies which have shown that gender atypicality in boys is highly correlated with homosexuality.  However, a number of the boys self-identified as heterosexual, even though they also recognized some same sex attraction.

For the girls, all of the desistors had become aware of the fact that they were heterosexually attracted to boys and wanted to be sexually attractive to boys.  Thus, they were the classic tomboys who grow up to be straight women.  But the persisting girls were all attracted to girls.

Thus, this study showed that the key difference between persistors and desistors among female bodied gender atypical / dysphoric individuals was sexual orientation, but among male bodied, it was not as clear cut, desisting boys included both gynephilic and androphilic sexual orientations.  However, what is clear is that persisting boys are all clearly unambiguously androphilic (HSTS).  Persistors will demonstrate same sex attraction, while desistors may or may not.  Thus opposite sex attraction is a key exclusionary sign for persistors.  Although we still would have some desistors who don’t show this sign, we have at least conclusively identified some.

Further, none of the study group was autogynephilic.

This last point is important.  Although many autogynephilic adults report having been gender dysphoric as children, it is rare, though clearly not unheard of, for them to have been noticed as such as children.  They are the “non-aparent” population as children.  However, for the HSTS population, of both sexes, MTF and FtM, their gender dysphoria was accompanied by obvious gender atypicality.  Since obvious gender atypicality is not found in autogynephilic boys, who are universally gynephilic, we can safely say that anyone who is obviously gender atypical and sexually attracted to the opposite sex is not going to be a persistor.

Another point can be clearly found in the Steensma study is that the developmental process, what ever it is, for desistors, is finished by age 14.  If a gender atypical 14 year old is still gender dysphoric and wishes to begin hormones and transition, we can be reasonably certain that he or she will not change his/her mind later.  Thus, based on the evidence, we can safely begin such interventions.  The sooner the better.


Transkids after transition

Transkids after transition

From the evidence, we draw the conclusion that for obviously gender atypical / dysphoric children, waiting until one is 16 or 18 years old to end puberty blocking protocols and beginning HRT is unwarranted and ill-advised.  Instead the evidence points to the age of 14 as the latest that HRT may safely be begun with little risk of iatrogenic injury to desistors.  Indeed, the evidence suggests that carefully evaluated, many of the desistors may be excluded by age ten to twelve.  Another point to come of these studies is that anatomic dysphoria (discomfort with genitalia, etc.) is correlated with persistence.  Thus, if delaying puberty is chosen, it should not be continued past the 14th birthday, and given proper screening, may be ended earlier, to switch to HRT.  For both cost and health reasons, it may be best to start on HRT for those who clearly fit the profile of a transkid, who request and understand the consequences of HRT, as soon as would be indicated for their gender of choice.  That is to say, that for MTF’s, HRT should begin at age 12, and for FtM, at around age 14, mimicking the natural maturational process for each target sex.

Addendum 2/23/2012:

If you are a young teen, finding this post:  Welcome!  To answer some questions.  Yes, you can start blockers, maybe with low dose HRT, as young as 10 years old, but should start with very low doses, gradually increasing to the recommended level for teenagers as you reach 12-14 years old.  Of course, you would need either your parents permission, or find a youth clinic that understands transkids’ issues, who would prescribe blockers & HRT on a “harm reduction model” .  (Seriously, that’s the magic words, “harm reduction”… as in… “I’m going to get hormones on the street if I don’t get them here.”)  Good luck!

Addendum 6/1/2012:

Please read my Advice to Parents of Transgender Children

Addendum 12/29/2012:

Please read my Advice to Transgendered Teens

Addendum 4/1/2021:

A newly published study, by Singh, but with individuals who had gone to a Toronto clinic years earlier (and thus evaluated with older criteria that we know are a bit loser than today’s) has data on persisting and desisting male youth.  As before, we see that most of them turned out to be primarily androphilic with the persisters being universally so.  And again, we see a difference in the age of evaluation with persisters being older at 8.85 years and the androphilic desisters being 6.96 years old (Cohen’s d = 0.84 a ‘large’ difference).  Interestingly, there were a number of gynephilic desisters in the study who were also younger in age at evaluation at 7.49 which is very similar to the desisting androphiles (d = 0.2 a ‘small’ difference).  Note that the difference, of d = 0.84 is essentially the same as the d = 0.81 found in the Steensma study.  Thus, the characteristic difference has been replicated and may be trusted.

Another difference was found in IQ.  Desisters were more intelligent than average at 110 while the persisters had the expected population average of 99 (100 is the population average, so this showed no significant difference).  Thus, there seems to be a selection effect that smarter kids are being brought in by their families at a younger age by families with higher socio-economic status (which correlates with higher IQ that runs in families).  Perhaps this is because they over-react to mild gender atypicality?  The authors of the study suggested that it was the fault of the poorer parents, “delaying” instead.  I stand by my assertion that it’s based simply on the fact that desisters desist and are no longer brought in for evaluation.

As seen in other studies, the persisters were more gender atypical and gender dysphoric at evaluation than desisters.

Addendum 6/15/2022:  Amazing News!  WPATH has finally accepted the science and has now lowered the recommended age for HRT to 14, as I’ve been arguing for over a decade:    https://apnews.com/article/gender-transition-treatment-guidelines-9dbe54f670a3a0f5f2831c2bf14f9bbb

Further External Reading:



Thomas D. Steensma, Roeline Biemond, Fijgie de Boer and Peggy T. Cohen-Kettenis, “Desisting and persisting gender dysphoria after childhood: A qualitative follow-up study”

Vicente Gilsanz, James Chalfant, Heidi Kalkwarf,Babette Zemel, Joan Lappe, Sharon Oberfield, John Shepherd, Tishya Wren, Karen Winer, “Age at Onset of Puberty Predicts Bone Mass in Young Adulthood”

Martha K. McClintock and Gibert Herdt, “Rethinking Puberty: The Development of Sexual Attraction”

Madeleine S.C. Wallien, Peggy T. Cohen-Kettenis,”Psychosexual Outcome of Gender-Dysphoric Children” Journal of the Academy of Child and Adolescent Psychiatry (2008)

Annelou L.C. de Vries, Jenifer K. McGuire, Thomas D. Steensma, Eva C.F. Wagenaar, Theo A.H. Doreleijers, Peggy T. Cohen-Kettenis, “YOUNG ADULT PSYCHOLOGICAL OUTCOME AFTER PUBERTY SUPPRESSION AND GENDER REASSIGNMENT” Pediatrics (2014)

Kelly Winters, “Methodological Questions In Childhood Gender Identity Desistence Research”  Blog Link

Brik, T., Vrouenraets, L.J.J.J., de Vries, M.C. et al. Trajectories of Adolescents Treated with Gonadotropin-Releasing Hormone Analogues for Gender Dysphoria. Arch Sex Behav(2020).  https://doi.org/10.1007/s10508-020-01660-8

Singh D. et al., “A Follow-Up Study of Boys with Gender Identity Disorder”, Frontiers in Psychiatry, https://doi.org/10.3389/fpsyt.2021.632784 


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