Before, I guess, mum and dad were everything, but now, in my case, I had two new girls and all of a sudden they're completely dependent on you and there's a third generation. It's a funny shift all of a sudden. You have the babies, you have yourself and then you have your parents.
Another cause of change, one less noticeable but fundamental, is the modern growth of population closely connected with scientific and medical discoveries. It is interesting that the United Nations has set up a special Commission to study this question.