The brain does not magically mature at 25. Actual neuroscientists note some 8-year-olds even have a greater “maturation index” than 25-year-olds. The myth misunderstands basic neuroscience but is still used for anti-trans policymaking like the Cass Report. https://slate.com/technology/2022/11/brain-development-25-year-old-mature-myth.html
