This is the part of the debate where certainty is the most dangerous word either side can use. The honest clinical picture is uncertain, evolving, and different for every child, which is exactly why it shouldn't be settled by a legislature in either direction.
Nearly everything now called pediatric gender-affirming care traces back to the Dutch Protocol, developed in Amsterdam in the 1990s and 2000s under Peggy Cohen-Kettenis and colleagues. The model was built for a specific, narrow population: children with consistent, early-onset dysphoria, stable families, and few co-occurring mental health conditions, screened extensively before treatment. The first outcome data, published by de Vries and colleagues in 2011 and 2014 in Pediatrics, followed roughly 70 children and reported improved mental health and high satisfaction after the full protocol.1 That is the evidence base an entire international standard of care was built on top of.
The population showing up at clinics today looks different from that original cohort: more adolescent-onset than early-childhood-onset cases, a shifted sex ratio, and higher rates of co-occurring depression, anxiety, autism-spectrum diagnoses, and trauma histories. Applying a protocol built for one population to a meaningfully different one is, at minimum, a reason for more caution and better assessment, not an argument that the original protocol was wrong for the population it was designed for.
A weak evidence base doesn't mean a treatment is wrong. It means we're more confident than the evidence actually supports, in whichever direction we've already decided to lean.
England's National Health Service commissioned pediatrician Dr. Hilary Cass to lead a four-year, independent review of gender identity services for children and young people. Its April 2024 final report concluded that the evidence supporting puberty blockers and cross-sex hormones for minors is of low or very low quality by standard evidence-grading methods, and recommended that puberty suppression be offered only within a formal research setting going forward.2 Similar, independently conducted reviews in Finland, Sweden, and Norway reached comparable conclusions about the strength of the evidence.
What gets left out when the review is cited by either side: it also found that the NHS had failed transgender youth through underfunding and poor service design, stated plainly that transgender young people are a real population with real clinical needs, and called for better-resourced care rather than withdrawal of care. It's a document that disappoints anyone looking for total vindication, which is usually a sign it was done honestly.
Utah offers an instructive counterpoint. When its legislature commissioned its own review to justify a 2023 moratorium on care for minors, the University of Utah's Drug Regimen Review Center evaluated 277 studies covering more than 28,000 transgender young people and found better mental health outcomes, including lower depression, anxiety, and suicide risk, among youth who received care before age eighteen. The legislature kept the ban in place anyway, and later made it permanent. The different conclusion isn't necessarily dishonesty on either side; European reviews and Utah's review applied different evidentiary standards to much of the same underlying research, which is its own lesson about how much "the science says" depends on which ruler is doing the measuring.
Historical regret rates for adult transition have been reported at or below 1%, though that figure describes a strictly screened population that no longer matches everyone seeking care today. Newer, adolescent-onset cohorts appear to show higher rates, though researchers don't agree on a consistent definition of detransition, which makes any single number less meaningful than it sounds in a headline. What the research on detransitioners consistently shows is that most cite external pressures, family rejection, social stigma, discrimination, rather than a mistaken original diagnosis, and many have been poorly served by a system with no clear path back for people who change course.
In June 2025, the Supreme Court decided United States v. Skrmetti, upholding Tennessee's ban on puberty blockers, hormones, and related treatments for minors seeking gender transition. The 6–3 majority held that the law classifies by age and medical use, not by sex, and so needed only to survive the least demanding level of constitutional review.3 The ruling doesn't resolve the underlying medical question; it means similar bans, now in place in more than two dozen states, are much harder to challenge on federal constitutional grounds.
Every major U.S. medical organization supports individualized, clinically assessed care for minors. Every legislature banning it is substituting political judgment for the clinical judgment of the people who actually examine the child. Neither extreme, instant affirmation or blanket prohibition, is good medicine.
The book walks through each stage of care individually, including surgery, fertility, and the WPATH evidence controversy, chapter by chapter.