> For example: Do nonbinary people have the same brain development as the people in this study, or do they diverge from cisgendered people of the same sex? The

> For example: Do nonbinary people have the same brain development as the people in this study, or do they diverge from cisgendered people of the same sex? Then I rest my case: this can't be done in any meaningful way. To give you an intuition as to why, how do we control that our nonbinary group actually corresponds to the gender theoretical definition of nonbinary? One could argue that this problem can be tackled by assuming two things: 1. people are being truthful when we ask them to categorize their gender 2. all nonbinary participants are categorizing themselves as such as a result of the same underlying process. If we do this, then we might observe a difference between the nonbinary group and the control group, but point 2 is a thorn in our side: we can't know that this difference actually corresponds to what is being claimed. For all we know, we could be measuring some general effect of sexuality that deviates from the norm. Hell, it could be some sort of process related to being primed as "not normal", i.e. the study reminds these people that they don't fit in and we pick that up in the form of anxiety or self-monitoring signals in fMRI. Again, the claim "my gender is of X" is unfalsifiable, and thus un-scientific. To summarize, you can certainly produce effects, but those effects won't meaningfully contribute to any understanding of sex/gender experience.