Further light is shed on this at the Catholic Education Resource Center website where the hilariously titled "Serving LGBT Students in Catholic Schools" makes it clear that science simply isn't relevant. Transgenderism is described as "willful gender confusion" that Catholic schools must never tolerate. It is recommended that schools stick rigorously to the Catholic line--no exceptions allowed--as the . . . wait for it: best protection against litigation. This is clearly what is on the minds of those who gave us these guidelines, not the psychological or physical health of transgendered students. 

http://www.catholiceducation.org/en/education/other-topics/serving-lgbt-students-in-catholic-schools.html