The sex binary is socially constructed, similar to the gender binary. Now, dimorphic sex characteristics are real, some people have testes and some have ovaries and putting them together is how you make babies. But the sex binary—the idea that along with testes comes an entire set of secondary characteristics which are mutually exclusive with another set of characteristics associated with ovaries—is socially constructed.
I recently had a consultation for electrolysis for permanent facial hair removal. My facial hair is too light for lasers. The technician was an intersex trans woman. She told me this herself. She does laser and electrolysis for most trans women in Philadelphia, she said. After remarking on how little facial hair I have, how slowly it grows in, and how light it is... she then proceeded to tell me that electrolysis would cost $100/hr and take about 50 hours spread out however long. So $5000 for my whole face. I would also have to change my skin care routine to stop doing anything that makes my face softer and more supple because that would increase the risk of damage... and 4 days before any appointment I'd need to stop shaving. So even at a very quick pace I'd be going through a lot more dysphoria for an entire year to permanently remove my facial hair and I'd be $5000 lighter in the bank. I've been weighing the pros and cons since and haven't really made a decision either way.
At the end of the day at work, all the workers loiter by the entrance of the library until all the patrons are gone and we can turn on the alarm and leave. It's a library, so the gender of the workers skews hard towards women. The only men at my library are the guard and the manager.
I was standing in a small circle with a group of my cis female coworkers, of a few different ethnicities and heritages mingle together. While idly chatting I mentioned I was getting my brows waxed after work. Just a routine waxing. A coworker mentions she got her eyebrows threaded recently for a wedding and it was painful, but not as bad as getting her lip waxed. I said I shave my lip. Another coworker said she plucks her lip and shaves her entire face from time to time. "I tell you I'd have a full beard if I didn't." Every single person in the conversation did some kind of regular and often intense facial hair removal in order to create the appearance of not being someone who grows facial hair at all, and also did things to make their brows less bushy. "I look enough like a man already I don't need a beard too."
The sex binary tells us that facial hair is an inherently masculine thing. That only men/'males' grow facial hair. Testosterone as a hormone does make everyone grow facial hair, and the more of it you've been exposed to in your life the more facial hair you'll grow. But everyone has some testosterone. It's a social fabrication that women do not grow facial hair and the vast majority of women put a lot of effort into maintaining this illusion. They feel bad when they fail to maintain it. I feel dysphoric when I can feel facial hair growing in, something which it takes about four days without shaving to even be visible. It's probably not much more than my cis female coworker. We both feel horrible when it happens. I can't say if I feel worse about it than she does. Though she is not considering spending $5000 to permanently halt the process via electrocuting the hair follicles at their root.
As Judith Butler writes, this binary is something that we perform. We do it. We bring it into existence by behaving in ways which accentuate and exaggerate the natural and unnatural differences between 'males' and 'females' and between 'men' and 'women.'
And that's all without even getting into the experiences of the intersex trans woman making big money helping other trans women ease their dysphoria.
It's hard to say how much of gender dysphoria is biological or sociopsychological. It's something I feel a strong need to alleviate and relief from treating either way. Hormones made something feel Right in me that's hard to attribute entirely to society. But the facial hair? It's hard to differentiate my dislike of it from every other woman i work with, undergoing painful frequent procedures to make it appear as though women do not grow facial hair, as a natural fact.