Quite a few people, actually! My main person for not telling... even though I know eventually I should, is my father. I think that his reaction would be scary and honestly I'd just like to make sure that my partner and I are far, far away. He's never been violent towards me or Handy, but I've kinda always had the fear in the back of my mind. He's basically a gun toting redneck who reacts very negatively towards anything lgbt related. We've never necessarily discussed trans issues, but I'm not eager to do so. I know before my SO came out, he thought she was gay and basically told me (in front of her) that gays are solely responsible for the moral degredation of society... and then proceeded to say he couldn't talk about it (as he nudged his head towards my partner). We hardly have a relationship, anyways, so I guess it's not much of a loss...
I think mostly we just plan on writing out the people who we can't tell. My gfs paternal side of the family is out, for sure, I don't even think they need the benefit of the doubt. They are fanatical christians... ya know, the kind who think harry potter and pokemon are demonic and gays can be cured. Well, even if they do find out, we don't plan on seeing their unpleasantness ever again. Her maternal grandparents are just so old, I honestly don't even think they would notice if she showed up presenting as female. So that is not really a concern, even though we won't tell her. She's been a bit dementia-ey lately (sad, I know) so I just don't think it is a problem. Her husband (my gf's step grandpa) is much more alert, but he is turning 90 soon, so who knows how much longer he'll be with us. Other than these few, we are pretty indifferent to who knows.