I won't tell my siblings even if we're close. My sister caught her son CDing and made a big thing (negative) about it to the family.
So do they need to know who I really am? No....but I think they might suspect something with my natural waist length long hair and pierced ears....
I'll tell them if they ask!
Only you can determine whether you should tell them, you know them best. Are you particularly close to one sister, if you told her do you think she would keep it to herself. If you think one sister is likely to accept and keep your secret, then start with her and gauge her reaction, but, also know that she might tell your other sisters too. It's difficult to know how someone is going to react to this news, for me personally I won't be telling my siblings. Do you think they would be surprised or is it possible they might have some idea, women in general are very perceptive and they might have picked up on something.
have 2 older sisters, shared a room with them growing up. Was very close to one sister and even considered telling her at one point, but, decided against it. As we've grown up we've drifted apart and I'm happy now that I didn't tell her, as she has since expressed negative comments on transpeople and crossdressers. Never considered telling my other sister as even though she might accept it, she'd hold it over me and definitely have never considered telling my older brothers!
As others have said thread carefully as you can't unring a bell! Good luck in whatever you decide.