I was listening to a recent episode of
The Skeptics Guide to the Universe podcast (anyone else a listener?), and they had a talk segment on the issue of whether sex is binary. They haven't really ever talked about the "trans question" before, and this, strictly speaking wasn't about transgender issues. But I could tell that they are sort of gingerly approaching the edges of those issues.
Anyway, I'm sure that everyone here is already aware of the existence of intersex people, with unusual combinations of chromosomes, or in some cases insensitivity to androgens (male hormones). I guess the main thing they proposed in the discussion is that sex isn't binary, but rather "bimodal", which seems like a reasonable enough statement. Here is a wikipedia article on what "bimodal" means:
https://en.wikipedia.org/wiki/Multimodal_distribution
Of course, most people are either male or female, but not everyone. But I already knew that.
Cara, the one woman on the podcast, and probably the youngest member too, actually seems to be the most vocal on the topic.
If anyone cares, here is a link to the episode:
https://www.theskepticsguide.org/podcasts/episode-869
And there is even a partial transcript, albeit incomplete:
https://www.sgutranscripts.org/wiki/SGU_Episode_869
It does however have a figure illustrating the concept of a bimodal distribution.
The discussion of "biological sex" begins at 1:00:45.