Is It A Choice Or An Obligation To Care For Our Aged Parents?

At what age should our parents stop caring for us?

Some children feel it is not an obligation to look after their parents when they are old and worn out but a choice.
I strongly don't agree with that.
If we do not take care of them in old age who would? After all, they nurtured us until we grew into who we became as adults.
We owe them that much. 

A woman (adult) feels her mum needs to continue to care and help her despite her age.
She herself is disabled, and her mother doesn't offer her much support, which hurts her.
She feels that parenting doesn't end when one's children become adults (especially if they become disabled) and that her mother should be helping her more.

I have sympathy for this woman. After all, what kind of mother doesn't want to help her child (of any age)?
But, I disagree that her mom has an obligation to help her, though. I wonder if that makes me strange. Don't get me wrong; I think caring for her daughter would be the decent thing to do, but I don't think it's her obligation. I'm not sure why I feel that way, though.

I feel a little differently about adult children being obligated to help care for their parents; I don't see it as my "job," but I do think it's the right thing to do. When my mom fell and broke her shoulder, I happily stepped up to do my part. I didn't do it because I owed my mom, though, or because I felt it was my duty. I did it because I love her; she's awesome, and she needed help.Some people think their kids are obligated to care for them when they grow old.

 I can understand that, but I don't agree. If you want your kids to care for you one day, then I think you need to be the kind of person they'd want to care for. If your kids feel good about themselves as a result of being around you, if seeing you makes them happy, if you love them unconditionally, I think you can expect that they'll care for you one day, simply because they love you.

On the other hand, if your love for your children is dependent upon them meeting your standards, if you're constantly judging them or making them feel badly about themselves, if you can't seem to find anything good to say about them, why in the world would they want to go out of their way to take care of you? Is your kid obligated to take care of you in your old age simply because you brought him/her into this world?

What do you think?