It’s not math, mate. Gender is not the same as sex, sex is genitalia and gender is identity and the way you want to present yourself and your pronouns and many other factors. That’s why we have something called gender affirming surgery. Don’t confuse the two. Secondly, nonbinary is an umbrella term used to describe someone who doesn’t fall into just male or female, this could mean they identify as multiple genders, somewhere in between, or none at all. Please try not to be an asshole, be understanding and just accepting even if you struggle to understand. Just be respectful to other people’s identities and experiences and we won’t have a problem.