If you are ever in doubt about whether to ask some burning question, first ask yourself if you would pose the same question about the body of a non-trans youth or adult, perhaps your own child or a student or neighbor. If the answer is no, don't ask. If you find yourself biting your tongue, keep biting.
For parents of kids who are transgender, gender education alone isn't going to provide that reassurance. What I think would really help are more everyday success stories -- people who can show trans kids, their parents and society as a whole that being transgender doesn't have to forever define you (unless you want it to).