Geektastic:
It is as silly as having children because you want an astronaut in the family.
You have no guarantee that - assuming the child lives long enough to care for you - it will be interested in doing so, capable of doing so or willing to do so - any more than you have any guarantee that the child will have the intellectual, physical and mental equipment to be an astronaut (to say nothing of the opportunity).
You're not going to convince me that "because I want someone to care for me when I am old" isn't a silly reason to have children.
I'm not saying it is never done, or that some children will willingly do it. I am saying that if that is the reason you're having them, it's not sensible. It would be more sensible if old age care is your primary concern to have no children and invest all the money you would have spent on them in an old age fund to pay for guaranteed care.
I don't think (most) people actually mean "care for", because that rarely happens these days. I think they mean "care about", in other words, remain socially engaged with.
But I could be wrong!



