I still haven't worked up the courage to tell either of my parents yet, but I told two of my sisters that I was transgendered and they both seemed to take it well. My oldest sister actually seemed pretty supportive and wanted to talk to me about how she secretly likes girls and thinks that guys are gross (she hasn't told anyone else but she's dropped a few hints). We have a pretty good trusting relationship.
I honestly have no clue how my dad would react, he is a very devout christian. I doubt he'd be too surprised, but I don't think he'd be very happy with me. He wouldn't try to change me because of my age, but I don't want him to disown me.