I grew up with a trans girl 35 years ago. We knew from the moment this child could express preferences that something was up. I'm talking 18 months - 2 years old, this kid is playing with dolls and trying on mom's high heels and makeup.

Back then, none of us had ever heard of a transgender person and had no idea this was even a thing, so we just assumed she was a gay boy. When she finally learned that trans people existed when she was in high school and told her mom, "Hey I'm a girl," it was like the most face-palmingly obvious thing ever. Of COURSE that's what we'd been seeing literally her entire life.

If she were growing up today, she and everyone around her would have identified her correctly at a much earlier age.