I come from a mixed family. Mother and Sister and Step-Father and Step-Sister. I was ten or so when my parents married so it doesn't feel different than any other family, but my Step-Sister and I aren't close. She lived in Texas most of the time growing up with her mother so that tight bond never developed. As an adult she moved back to Washington so it improved, but not greatly. We are simply different people. Occasionally she makes the effort, but more often it's sullied by insults. My favorite one was, "What are you, gay?" because I was eating oatmeal instead of sausage and French Toast. "Um no, there is a reason why I'm not 250 lbs." is the answer I'd like to give but I try to avoid stirring the pot at home. I want to be around my parents.
I suspect that my step-father is likely to live another ten years or more. I want to maintain a decent relationship until then with my sister. But after that, I don't see us talking much. Today might have been the final break point. She sent me an email yesterday about the greatest tax increase in history which is about to happen. I debunked it with references. She sends back a three line email. First line basically impressed with the info. The second and third lines, "So you support the blacks now? Where was your rant on the welfare system?"
I don't know what to say to that. But what are the limits of the term family for you? Do you have family that you just don't interact with and what got you there?