Judging from this, I guess childhood experiences can decide one's preference. Your first attractions were with your teachers. I guess this can happen to other people if they had attractive teachers, which are very rare. (I'm not saying that all teachers are bad. I had some teachers who were psychotic).
Go ahead and tell your parents. If they disapprove, show them by having a happy life with her. They'll approve once they find out how she makes you happy.