I'm seriously considering it (still the 10th for me). I'm relatively certain that my mom will be completely indifferent as she's dropped numerous hints that she is about homosexuality, and I have expressed indirectly that I'm bisexual and our relationship hasn't suffered any. In fact she's stumbled across my porn and toys on at least three occasions and made light of it every time. Considering that I've only known my stepdad for about a year, I'm intent on getting her alone and bringing up the topic and going from there. I'm sure he thinks the same way, but I'm not sure what he would think if he knew that I was wearing his daughter's old clothes.
[EDIT]
Well, I preempted coming out day and made mom pull over at the shopette on the way home from getting dinner and told her. As I suspected, she was completely indifferent to my crossdressing, and as impeccable as her memory is, she knew at the very least that I was at the panties stage. When we were moving to hawaii she went looking for a book in my suitcase and stumbled across some of my panties as well as my big blue buddy (use your imagination) so she knew I wasn't a normal boy. Felt good to tell her, so I definitely won't have to be explaining any clothes or panties or other things she might glance in my room, nor question the pink disposable razor in my bathroom. We both agreed though that she would let me do the job of telling my stepdad Tony after I've gotten my own clothes. I don't think he'd care much about it, but knowing that I'm wearing his daughter's old high school wardrobe...that might pose some complications. At least now I know that if I tell her I want to buy some new outfits (completely legitimate since I haven't gotten any new clothes in a year or two) she won't be bothered by me buying some panties, bras, bra pads, and skirts/jeans/tops/etc. She didn't mind that I coopted her makeup basket either, since she despises wearing makeup. The benefits definitely outweigh the consequences.