I wouldn't take anything for granted, but I will share a convo I once saw a father and a son exchange (father being old and son being in his 50s), discussing about same-sex-civil-union/marriage. It'll be paraphrased a lot.

F: [disagreeing with it, grumpy]

S: I don't really feel worried about it, civil unions have nothing to do with the church, there's no reason to feel like this is any threat.

Father then decided he had no response. This was a longer exchange/vent but I really can't remember it properly. It was posed as an 'otherness' though, gay =/= catholic, but I'm not sure what the son's views would be if he wasn't trying to convince an old person that this had no impact in their beliefs or life.

I think things will depend highly on the family and the culture. In my experience, most people will feel like it's none of their business. I would also guess some people who are closer might feel uncomfortable, make comments or questions, or feel sad/want to pray for you. But I'd imagine the general vibe can be either "I disapprove, but I accept", or "I accept, but disapprove", or in some cases "I accept and love you".

I think people can really be loving and these days they're understanding that it's something you really can't control. They might be afraid of what you do with the sexual orientation - as in worried for you, uncomfortable. They might disapprove you having a boyfriend but they won't disapprove "you".

I wouldn't get my hopes up too much. But I wouldn't put them too low either, at the point of 'disowing' or 'rejecting' or strongly diapproving and shaming you.