We go through the changes of our lives. They are programed into our DNA. Billions of people didn't just happen to decide to the leave the nest in their late teens and early 20s, and just happened to make a nest of their own. Our attitudes in life change with age. When we were young, we couldn't wait to see what the next year's cool cars would look like. We looked forward to change as progress. We didn't want anything dated. As we start into our 60s and up, we start the process of 'disengagement'. We become increasingly nostalgic and start to withdraw from society. In another thread, we are discussing feeling lonely. It's what we are programmed to do. We didn't all lose our baby teeth at the same age, because we "thought" it was a good idea-it's what we were programed to do.