“By the time this hits the parents, there's … almost a religious fervor that they're up against.”

Alasdair Gunn, also known by his pen name Angus Fox, is a vice-director at Genspect, an organization seeking to broaden the treatment options available for people questioning their gender—beyond “gender-affirming care.”

Mr. Gunn helped inspire parents to share their stories in the new book, “Parents with Inconvenient Truths about Trans: Tales from the Home Front in the Fight to Save Our Kids.”

The gender industry has “parasitized people’s emotions,” Mr. Gunn argues. “And it's managed to remain as though it's some very respectable normal field of medicine, as though it's knee replacement or orthodontics or something, and it's not.”