But for kids, especially younger ones, the issue is much more problematic. Gender confusion is often temporary. About three-quarters of little kids who have issues with their gender – boys who want to be princesses, girls who throw their dresses in the garbage – will be comfortable with it by adolescence, according to Dr. Zucker. (Many of them will grow up to be gay or bi.) Gender confusion can also be a handy label for whatever ails a child (or her family). That’s why Dr. Zucker takes a watch-and-wait approach. He even advises parents of princessy six-year-olds to say, “You’re not a girl. You’re a boy.”

And in the hotly politicized world of gender politics, that makes him, in many people’s eyes, a dangerous reactionary. They argue that a child’s identity must be honoured, and that treatment should start sooner rather than later. They equate the watch-and-wait approach with the widely discredited practice of reparative therapy, which was a failed effort to turn gay kids straight. With the advent of powerful new drugs that delay puberty, the stakes in this debate are even higher. Start them early on puberty-blocking drugs, and their eventual transition will be easier. But which kids? What if you’re pushing them on a path they don’t need to go down? At what point do you start taking life-altering decisions for a child that will have enormous physical, social and emotional consequences?

Alice Dreger is a bioethicist and professor at Northwestern University’s Feinberg School of Medicine in Chicago. She calls herself an (im)patient advocate who prefers evidence to ideology. She is a strong supporter of transgender rights. But she thinks the pendulum has swung too far.