Generations

[Rusty Claymore]

Today was the anniversary of my grandfather's 100 birthday. We had cherry pie. n.n/)

But, I'm not even 20, so in my family there is a huge gap in the generations, since my folks are approching the 60's. But just about everyone else I know is only 20-30 years younger than their parents, and even the grandparents are just 20-30 years from the parents.
Thinking about the possible trends that could be discovered is an interesting proposition. (Hey, saying 'thought' after 'thinking' would have been dumb, so bear with the not-quite-right word...)
So, how long are your clan's generations?