Alex, they wrote, “has been gender-fluid for as long as we can remember, and at the moment he is equally passionate about and identified with soccer players and princesses, superheroes and ballerinas (not to mention lava and unicorns, dinosaurs and glitter rainbows).” They explained that Alex had recently become inconsolable about his parents’ ban on wearing dresses beyond dress-up time.

The night before Susan and Rob allowed their son to go to preschool in a dress, they sent an e-mail to parents of his classmates.