I'm not sure where the idea that parents are a "burden" came from. I never said that.

I consider helping my parents a responsibility. That is one thing I got out of my upbringing - I take care of my responsibilities. There are times when I think it's wonderful - there are times when it definitely is not. Last night I could hear a conversation they were having in another room. They were discussing the three kids they had. Long story short - my brother is a bully, I'm emotionless and care more about animals than people, and my sister who passed away was the only good child they had. Eh...wasn't the best thing to hear - but it doesn't change my responsibility.
Bee just pointed out the same thing that I said. Even in large families - sometimes a disproportionate amount of caregiving falls on one sibling. Not always, not every time, but my point is that it's not about family size...it's about who steps up.
In my mother's family - she took care of her mother - her siblings did not step up either. My brother has watched over my parents for years because they live next door to each other...he's not in a position to do that now. We ARE sharing the responsibility even though we sometimes have different ideas of what role the caregiver needs to play.
My son and his wife help me now. They have their own lives and their own place and their own responsibilities - but they help me with jobs that are larger than I can handle on my own. However, I do not expect and will not put the expectation of my
personal care on them as I age. Just my philosophy - don't need anyone to agree or disagree with that. It's what I expect for my family and my circumstances.
Totally agree with NH that blood doesn't always mean family. There can be special people in our lives that have no shared blood - but do have a deep bond and will always be there for each other.