My youngest sister is the only person in my family that knows. She's been completely supportive since the beginning and if she was confused by anything, it was that she has been around a lot of trans people and never around crossdressers. She's also REALLY into clothing so she's both enthusiastic and knowledgeable about what I want to wear. Things are still a little weird, mostly on my side of things, and I try to not smother her with everything, so we still don't talk about it often.
I know the rest of my family could handle it, since we're very socially liberal (at least in theory, as is often the case), but it would still be much more awkward. My dad probably wouldn't care, as he is extremely pragmatic about things and mostly cares that work gets done, my other two sisters would probably be amused, buy my mother and brother would probably ridicule me for a while.