My mother's parents died before I was born, and my father's parents died when I was around 10 years old. With the exception of my great-grandfather, my other great-grandparents died in the 1940s and '50s. They barely got to know their own grandchildren before they passed.
My parents were unusual for their generation in that they waited until their mid 30s to start having kids (despite having been married for 9 years already). On my dad's side, he was the final child of my grandmother's third marriage; she was 42 when my dad was born (again, unusual for the time).
No real point to this post, I guess. I just think it's interesting that people's experiences can differ so much. I only knew half of my grandparents, and even then only as a child; the idea of people being able to meet their great-grandparents wasn't even something I ever considered when I was younger. I don't recall for sure, but I don't think many if any of my grade-school friends had great-grandparents around either. I've always had a very small extended family, and hearing stories from friends as a kid about family gatherings always made me feel like I was missing out.