Yes we do this also. However, our hope is that our children will be decent people who will do this of their own volition as they see appropriate, not because it is ‘expected’ of them. In same way, we paid/will pay for their colleges (with no loans at a mutually acceptable schools) with no expectation of future payback. Our only expectation is that they will make good use of the opportunity we are providing them with. DS did and we trust DD will also.
They are not part of my retirement plan but I would hope that, if for some unforseen reason we the parents are in some sort of need, that they, out of love and decency, will pitch in in whatever form is needed.