Yeah, the endpoint is definitely not well-defined.

I regularly use the example of my wife and myself: She’s actually a couple of months older than I am, but she’s basically an X whereas I am classic Boomer, and the difference is our parents. My parents grew up during the Depression and my dad fought in WW2 and then they got married; Angie’s mom was TWO when Pearl Harbor was attacked and was in college in the ’60s. I was a late-life surprise baby but she was born to a young mother fresh out of college.

I still carry with me generational habits of people raised during the Depression, like habitually shaking the milk when I take it out of the refrigerator because my parents predate homogenization and they were used to having to worry about the cream separating overnight, for instance.