We always want to see our own image in others. We love them as much of our own self we see in them. A father wants to see himself in his son. He wants him to be what he is or what he himself wanted to be. He wants his son to achieve what he himself wanted to, but could not.
But it's not always possible. Everything changes with time, including the environment and life styles. Every new generation's thinking is different than the previous one's. Their interests and ways of doing things, their ambitions and general outlook on life may not be same as the previous generation.
Hence the differences and clashes in interests and ideologies are bound to happen.
To keep loving and healthy relationships, an ideal sitution would be to meet in the middle. But practically the older generation has to make more adjustments. They have to understand that their times have passed and they need to accept the change and sacrifice their own ideas in order to maintain the harmony.