What does family mean?

I think I don't understand people. When I say I do not like my family, everyone goes: 'Come on, how can you not like your family? They are your family!'. So what? Just because they are my family it doesn't mean I have to love them, I mean, I didn't choose them!
I think familiar relationships are overestimated. They say your parents are someone you can always rely on, someone who will always be there in bad times. I wish this was like this, it would be great to have somebody to trust any time, but real life is not like this. At least, mine.
I don't think having a good relationship with your family is such an important thing. As you didn't choose them, it's only a matter of luck, whether you like them or not. The curious thing is every time I have talked about this (even if talking with people who don't get on with their families), they all say family is important and they love theirs. And I really don't understand it, if you don't like some people, why should you pretend you love them, just because you are relatives? It doesn't make sense to me.