All your examples of things you hid from your parents are dangerous, illegal, and ‘wrong’. You trying to lump personal identity in with things that can lead to jail or teenage pregnancy is very telling.
Should teachers also report when your child makes friends with a student of a different race or religion? Why or why not and if not, how is that any different from this? You keep referring to teachers ‘making decisions about the child’ but nothing is being ‘decided’ by teachers here. It’s the children who are deciding this for themselves because they’re also people with autonomy.