On the Science of Changing Sex

Biological Reality! Transsexual Women’s Breasts Are Female Breasts

Posted in Transsexual Field Studies by Kay Brown on May 19, 2022
Kay Brown with her adopted daughter Liz

Yesterday, a post about a transwoman breastfeeding a baby went viral. As one could imagine, transphobic commentators had many nasty, ugly comments to make. However, it also became clear that they were under the misapprehension that transwomen couldn’t breastfeed, “Your male body can’t produce milk!” “You don’t have female breasts.” “Where is the colostrum?” “Where are the lobules?” Why do they object to this knowledge and go into deep denial? Could it be because of their reliance on an ugly propaganda slogan of “biological reality” which they say transsexuals are in denial of… yet, here is something that they claim can’t be done, a true female biological function that can only be performed by women, by only natal female women, that is being done by transwomen. Learning that transwomen can and do perform this uniquely female, womanly function of sharing life giving milk with a baby upsets their world view and their propaganda.

So, sad as the need to explain such basics of mammalian biology to the world is, it must be done, as these ignorant and false assertions from these transphobes proves.

First, it important to understand that each and every gene that a woman has is also found in males. Females have two copies of the X chromosome while males have only one. But they still have that one. Further, many of the genes needed to express female phenotype aren’t even on the X chromosome, they are spread over the various autosomal chromosomes. To get a male, one need the genes on the Y chromosome, most particularly the SRY gene that first tells the proto-gonads to become a testes instead of the default ovary. But after that, nearly all the rest of sexual development is under the control of hormones produced by the testes.

If the body lacks the usual androgen (testosterone) receptor gene(s), even if that body has all the other typical genes and chromosomes for a male, that body develops in a rather typical female pattern. This condition is called 46XY CAIS, complete androgen insensitivity syndrome. They have typical testes in a seemingly typical female body phenotype, and most importantly for our discussion, women’s breasts at puberty.

Breast tissue does not care if there are XX vs. XY chromosomes. Breast tissue, like all secondary sexual characteristics that develop at puberty, are under the influence of sex hormones. Sex hormones can and should be viewed as specialized growth hormones. Various tissues express different sensitivities to the various sex hormones and will grow or not grow depending upon the presence and balance of these specialized growth hormones. In particular, breast tissue responds to estrogen and progesterone and are somewhat suppressed by androgens.

Circling back to transwomen, we note that Hormone Replacement Therapy (HRT) uses the very same hormones that induce breast tissue development in women. Transwomen have all the genes and breast tissue stem cells needed to develop fully functional FEMALE breast tissue. When a transwoman begins HRT, her breasts respond and begin to develop. After sufficient time, her breasts are histologically identical to adult natal female breasts. That includes the potential for lactation.

A woman does NOT have to have given birth or even have been pregnant to lactate. It certainly helps, given that certain hormones automatically are produced in amounts that prepare the breasts to produce first colostrum then milk, but isn’t an absolute requirement. The key requirement is that of tactile stimulation that a baby’s suckling produces and that once a flow of colostrum is present, that it be drawn out, either by a baby suckling or by manual expression / pump.

If a woman is adopting or working with a gestational surrogate, she may elect to breastfeed her baby by following a regimen of stimulation, expression, and pumping. In some cases, medication may aid in this process.

Many transwomen have produced colostrum due to HRT which in some cases, primes the breasts in the same manner as being pregnant. (I myself have produced colostrum.) If a transwoman is adopting, working with a gestational surrogate, or has a female partner who is expecting a baby, she too may elect to breastfeed her baby in the same manner as would any other non-birthing woman.

The milk produced by a transwoman is identical to milk produced by a natal female. Transwomen have been quietly, successfully, and safely breastfeeding babies for decades. They will continue to do so.

Biological Reality.

Further Reading:

Baby Hunger


de Blok, et al, “Frequency and outcomes of benign breast biopsies in trans women: A nationwide cohort study” The Breast: Official Journal of the European Society of Mastology, (2021) https://doi.org/10.1016/j.breast.2021.03.007

Wambolt, R. et al, “Lactation Induction In A Transgender Woman Wanting To Breastfeed: Case Report”, Journal of Clinical Endocrinology & Metabolism, (2021), https://doi.org/10.1210/clinem/dgaa976

Kulski, J., et al, “Composition of breast fluid of a man with galactorrhea and hyperprolactinaemia”, Journal of Clinical Endocrinology & Metabolism, (1981), https://doi.org/10.1210/jcem-52-3-581

Breastfeeding Without Giving Birth

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Transsexual Kids DO Know

Posted in Editorial by Kay Brown on May 5, 2022

Having real data trumps ideological assertions. The “ideology” I speak of is that of transphobic individuals who falsely insist that transkids are too young too “know” – to know who they are, to know their hearts, to know what social gender they best fit in as, to know their minds regarding what constitutes their best chances for future happiness and social success. These ideologist don’t actually say this in true sympathy or empathy with transkids. They say it because they don’t want transkids to grow up to be transsexual adults. They don’t want transkids to grow up to be those people. Data trumps this false assertion, this false empathy.

Over the past decades, data about transkids has been growing. One thing that former transkids (those individuals who had been “early onset”, both gender atypical and gender dysphoric before puberty and are now adult transsexuals, have been saying is that they took to social transition, at whatever age they were able, most as teens or early ’20s in the past, given parental and societal opposition, with great relief and ease. Indeed clinicians have long documented this phenomena. They have also pointed out that they would have benefited from social transition at a far younger age to avoid social difficulties growing up. They actively point out that such social transitions would also differentiate those who would be ‘persisters’ from ‘desisters’, that attempting to socially transition, even before their teens, works as a “Real Life Test”. Those that are likely to desist, are not likely to find social transition all that appealing nor will they remain socially transitioned, if they do. We now have the data to back that up.

Dr. Olson’s latest paper in Pediatrics, “Gender Identity 5 Years After Social Transition” followed a large cohort of transkids starting at age three to twelve as part of an ongoing longitudinal study. The paper is available online, NOT behind a paywall, so it is well worth reading for yourself if you wish to follow-up on my explication of it. But before we dive into the data, I need to deal with an unfortunate misuse of language that the authors have chosen to use.

In the transsexual community, the term “retransition” has a specific meaning that the authors of the paper have turned on its head to the opposite meaning in some cases and its proper meaning in others. Specifically, in the transsexual community, the term means one has once again began living as the opposite of their natal sex after having “detransitioned”, reverted back to living as their natal sex, for a period of time. But the authors of the study use the term “retransition” for BOTH situations. The authors made clear they know that they are making this confusing misuse of the established vernacular, but chose to do it anyway. I will not. So, when I am quoting them, I will substitute the proper term {detransition} for clarity by including it in curly brackets to show when they are misusing the term “retransition” in the original text.

Let’s take a look at the abstract by way of introduction of the study and the data,

Background and Objectives. Concerns about early childhood social transitions amongst
transgender youth include that these youth may later change their gender identification (i.e.,
retransition), a process that could be distressing. The present study aimed to provide the
first estimate of {detransitioning} and to report the current gender identities of youth an
average of 5 years after their initial social transitions.
Methods. The present study examined the rate of {detransition} and current gender identities
of 317 initially-transgender youth (208 transgender girls, 109 transgender boys; M=8.1
years at start of study) participating in a longitudinal study, the Trans Youth Project. Data
were reported by youth and their parents through in-person or online visits or via email or
phone correspondence.
Results. We found that an average of 5 years after their initial social transition, 7.3% of
youth had {detransitioned} at least once. At the end of this period, most youth identified as
binary transgender youth (94%), including 1.3% who {detransitioned} to another identity
before returning to their binary transgender identity. 2.5% of youth identified as cisgender
and 3.5% as nonbinary. Later cisgender identities were more common amongst youth
whose initial social transition occurred before age 6 years; the {detransition} often occurred
before age 10.
Conclusions. These results suggest that {detransitions} are infrequent. More commonly,
transgender youth who socially transitioned at early ages continued to identify that way.
Nonetheless, understanding {detransitions} is crucial for clinicians and families to help make
them as smooth as possible for youth.”

Note that that there are about twice as many MTF transsexual children (“transgender girls”) as FtM transsexuals in the study. This is in keeping with decades of demographic data that show that there are more MTFs than FtM transsexuals. As adults, there are usually so many more “late onset” MTFs than “early onset” such that the ratio is much higher. (Note that I am excluding the recent fad of large numbers of girls and young women falsely claiming a “trans” or “non-binary” identity.)

Note also that of those who detransitioned / desisted, they did so before age 10.

“All but one of the 8 cisgender youth had {detransitioned} by age 9 (the last {detransitioned} at 11)”

This is in keeping with earlier data that showed that desisters always did so before puberty and the age of seven to ten was critical in this process. While persisters reported that the ages of ten to thirteen saw that their gender dysphoria increased and cemented their transsexual (cross-sex) gender identity. Note that of this cohort who had attempted social transition, only 2.5% of them had truly desisted. That is to say, pre-pubertal social transition was overwhelmingly comprised of persisters. The “Real Life Test” works as was predicted years ago, as the study authors also suggest, in a typical “science speak” way,

“It is possible that some youth initially try socially transitioning and then change their minds quickly. Such youth would be unlikely to be enrolled in this study because their eligibility period would have been quite short and therefore the odds of finding the study and completing it would have been low. This means the children in our study may have been especially unlikely, compared to all children who transition, to {detransition} because they had already lived – and presumably been fairly content – with that initial transition for more than a year.”

Further Reading:

Desisting vs Persisting in Gender Atypical Children

Transkids Transition Because They ARE Transkids


Olson, K., et al, “”Gender Identity 5 Years After Social Transition”, Pediatrics (2022), 10.1542/peds.2021-056082

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