I know lots of you will be familiar with Colin Wright already - one of few biologists, like the fantastic Emma Hilton, who counters gender identity theory, and tirelessly explains the reality of the sex binary.
Some of his stuff is subscription only, but he's posted this 30 minute talk which goes over all the main points with great clarity (intersex, the genderbread person, sex as a spectrum) so a really good starting point for anyone new to this.
https://www.realityslaststand.com/p/the-sex-binary-what-it-is-and-why?utm_source=substack&utm_medium=email&utm_campaign=email-half-post&r=i8ccx