Natasha 
🇪🇺
Looking for explanations…No, the author has it wrong. What she learned in middle school was wrong and should never have been presented to her as fact.
DB SchweinNobody is going to teach middle schoolers graduate level science - the students wouldn't understand it, and the teachers don't have the time!
What got lost somewhere is the lesson that "we teach you the basics, and if you want to learn more that's what the library/high school/college/etc. is for"!
Teaching that there are only 2 genders isn’t basics. It’s just wrong. I learned that there are intersex humans and that gender isn’t always clear at birth when I was still at school. In the 70s, & not in a radically hippy school.
Basic, common biological differences & reproductive differences can be taught, in science. The fact that gender is a construct can also be taught, probably not in science.
I was a middle school English & Humanities teacher. Taking time to discuss this sort of stuff was part of my job, mostly in “mentor” or “home group” settings, but sometimes in history. Making time to discuss it in depth was hard, but I could certainly find time to alert students to the idea of social constructs.