“Get out! You’re a girl!”

The shout rang out from the men’s room in the Chicago airport, and I heard it all the way in the women’s room next door. My husband had taken our son, Sam, who is seven, to the bathroom between flights. It was not the first time I’d heard such a shout. I ran out with my daughter to find out what was happening to Sam.

Sam looks like a girl. Even that day—wearing khaki pants, a blue t-shirt, and grey sneakers—his long hair and pretty face trumped his boyish clothes. People inevitably think he’s a tomboy. His natural femininity makes boys in restrooms across America feel justified in screaming at him, believing that their knowledge of his gender is greater than his own, lunging, as one boy did at a New York airport, ready to strike until my husband stepped in. Kids in his own California elementary school tell him he’s in the wrong bathroom, ask him if he’s lost or stupid, and, if he stands up for himself and says he really is a boy, tell him to drop his pants and prove it.

A few years ago I read an article by New York Times writer Patricia Leigh Brown. Brown wrote about adult transgender and gender-nonconforming people who face discrimination when they try to use gendered public bathrooms. I had no idea that it would one day be relevant for my own child.