Nope. They don’t even check your chromosomes when you’re born. There are also many possible genital configurations at birth. Odd that we don’t treat every one of those possibilities uniquely and instead force them to get surgery so the doctor can assign a gender to them. You’d think if it was all basic biology we would just have a unique gender for every one wouldn’t you?
There are also many, many more possible configurations of your chromosomes than half a dozen lol. You can also have XY and be assigned female at birth. And vice versa.
Your doctor is assigning you a gender. Thats what he’s doing. He calls you either a boy or a girl based on your genital configuration and then as I said in my previous comment that assigned gender goes on to affect every single aspect of your life for the rest of your life.
You don’t seem to know what we’re even talking about. Sex is not binary and is not enshrined in biology. If we wanted to talk about biology, if the point was biology, if the doctor assigning genders to babies primary concern was biology, then he would assign a unique gender to every single possible genital configuration at birth. All of them would be unique. Instead he’s assigning you a gender so that society can treat you a certain way. It’s that simple.