Gender or sex?

I’m writing an article for a tech website about some geeky marketing stuff, and I need to describe how Google Analytics collects demographic information. Generally speaking, it collects age and … what? Sex or gender?

It says “gender,” but it only has two: male and female. So what is that?

The gender police will tell us that there are scores of genders, so “male or female” can’t really be “gender,” can it? I mean, is Google transphobic, or … whatever?

Sex is conveniently binary. So if they’re dividing things into male and female, it really should be sex, not gender, and that’s the way I’ll write it in my article.

But I wonder what the editors will do when they see that.