I do not remember my grandparents acting as juvenile as I do

My grandparents were immigrants. My grandmother spoke almost no English, and my grandfather spoke broken English. The people they stayed in touch with were other immigrants of their generation.

So they remained largely insulated from contemporary culture in the U.S. Being "apart" contributed to being "old fashioned."

But you and I don't feel that cultural divide, so we can jump right in and act like kids!