It feels pretty creepy to find out that Twitter has been using people’s data to assign them gender identities. But this isn’t unusual. It’s entirely common for websites to infer their visitors’ and users’ genders for advertising purposes. Google does this for you too (and you can check what assumptions Google’s made about you here).

The fact that Twitter allows you to edit your assumed gender or write in how you identify is actually a step up from what some other tech companies offer users. Google only allows you to indicate that you are male, female, or “rather not say.” Facebook has allowed you to write in your own gender field since 2015 (though gender has always been part of your Facebook profile, unlike Twitter, who has never asked you to specify). And overall, transparency about how these platforms use our data is good! Yay transparency!

We all know that companies like Twitter and Facebook are using our data to allow advertisers to find and target specific people – that’s social media companies’ business model. In additional to the gender and age that they infer, there’s a whole list of things they think you’re interested in that advertisers can use. Twitter thinks I’m interested in “investing” and “men’s pants” even though I’m not, but that’s low stakes and more funny than anything else.

But for trans and gender-nonconforming people, seeing that a platform for free expression like Twitter has been making gender assumptions for them – whether it’s right or wrong – can be jarring and upsetting.