Every Tuesday, Sam has hot lunch at school: a hot dog with no bun. Bunlessness is important, because Sam has celiac disease, which means he can’t eat wheat.

Last week, Sam’s hot dog came in a bun. According to his doctor, he cannot eat anything that has even touched wheat, so he went without lunch that day. I called Jeff, the lunch provider, to discuss the situation. Jeff was very nice, and promised to work harder to provide a safe lunch for my daughter.

My daughter, who is actually a boy. Jeff and I were a couple minutes into the conversation before anyone uttered a pronoun, and it was Jeff who did it, Jeff who said he cared very much about my daughter’s health. Jeff has never met Sam. Somehow, he just knew that Sam was a girl.

I understand the woman we met on a plane last week, who saw Sam’s pink shoes and long hair and thought he was a girl. I understand the many people we meet on playgrounds and in restaurants who assume the same. But someone who’s never even seen him?

The only time that anyone’s ever “mistaken” Sam for a boy was at 4am in a diner in San Francisco’s Castro neighborhood. (It’s a long story.) Here, in the most densely gay part of the United States, the waiter took one look at this blond pony-tailed child in pink Crocs and asked, “Does he want whipped cream on his hot chocolate?”

Never mind what a seven-year-old was doing in an after-hours diner. How did he know Sam was a boy? Somehow, he just knew.