'No, I'm a Girl': What Influences Gender Identity?

F. Perry Wilson, MD, MSCE


November 20, 2019

Welcome to Impact Factor, your weekly dose of commentary on a new medical study. I'm Dr F. Perry Wilson.

This week, we're going to delve into an issue that is fraught with cultural, sociological, and scientific controversy. It's an area that has become something of a political football as well. Before we dig into this study looking at gender development among transgender children, appearing in the Proceedings of the National Academy of Sciences, let's acknowledge that emotions around this issue run hot but that we're not here to talk about emotions.

The study centers around a cohort of 317 transgender children between the ages of 3 and 12. Two hundred and eight of them (65%) were transgender girls. To define our terms, this means they were born with male genetics and genitalia, but at some point before enrollment in the study, they transitioned socially to living as a girl.

The central question that was examined was how strongly these kids experienced that gender identity.


This was assessed across a variety of domains, including toy and clothing preferences, peer preferences (ie, who they preferred to play with), and how similar they felt to other members of their lived gender.

Before I show you the results, I want to point out that we could hypothesize in either direction here. One could imagine that transgender children who have transitioned might demonstrate a particularly strong affinity for their current gender, perhaps in an effort to reclaim the experience denied them when they were younger. Alternatively, they might have a weaker affinity for their current gender due to the culturalization of the years living as the opposite gender.

What the authors found was fairly striking: Transgender kids across almost all domains had basically the same affinity for their current gender as cisgender controls and their cisgender siblings.


Transgender girls liked playing with dolls, wearing dresses, and playing with other girls just as much as cisgender girls. Transgender boys felt that they were as similar to other boys as cisgender boys.

I spoke with lead author Selin Gülgöz about the results. She was struck by the remarkable similarity in data between the transgender and cisgender kids.


Of course, it's important to note that these families chose to participate in the study; it's unlikely that they reflect the experience of all transgender children out there.

I think there's a potential reaction to this study that we should address. Basically, how do 3-year-old kids have any idea what gender they are?

Well, prior research on cisgender children has shown that gender identity—the sense that "I'm a girl" or "I'm a boy"—actually emerges quite early, at around 2 years of age.

But I think there is an intuition that this is socially induced. In other words, my 2-year-old thought she was a girl because I told her she was a girl and dressed her like a girl. Are parents of transgender children affecting their gender identity, or is it more internal?

The study offers two ways to look at the question. First, they examined the cisgender siblings of the transgender kids. Those siblings had just as strong an affinity for their own gender, suggesting that these aren't families that are particularly different in regard to gender socialization.

Second, in a rather clever analysis, the researchers had blinded scorers look at photographs of the children from before transition, on "special" days when they were unlikely to dress themselves, like early birthdays and Halloween. Here's Dr Gülgöz again:


This is evidence that these kids' gender identity was not imposed upon them; it began internally. Transgender girls feel like girls and then adopt the socially acquired signals of femininity, not the other way around.

Of course, we're only beginning to understand the complex interplay of biology and gender. It will take more time—and probably more open minds—before a deep understanding emerges.

F. Perry Wilson, MD, MSCE, is an associate professor of medicine and director of Yale's Program of Applied Translational Research. His science communication work can be found in the Huffington Post, on NPR, and here on Medscape. He tweets @methodsmanmd and hosts a repository of his communication work at

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