楼主别担心，是长辈们自私，非常自私。推荐看看罗素的这篇文章 [<How to grow old>]( https://sites.google.com/site/gobenyan/essay
"The other thing to be avoided is clinging to youth in the hope of sucking vigour from its vitality. When your children are grown up they want to live their own lives, and if you continue to be as interested in them as you were when they were young, you are likely to become a burden to them, unless they are unusually callous. I do not mean that one should be without interest in them, but one ’ s interest should be contemplative and, if possible, philanthropic, but not unduly emotional. Animals become indifferent to their young as soon as their young can look after themselves, but human beings, owing to the length of infancy, find this difficult."