My husband has taught human reproduction and development to the Cambridge medics for over three decades. When people start banging on about "only two biological sexes" he starts with "which sex: genetic, hormonal, or gonadal"?
Biological sex is not binary. www.scientificamerican.com/article/sex-...
www.scientificamerican.com
Biologists now think there is a larger spectrum than just binary female and male
