I think if you look at the fact that 7 of the 12 people this has ever happened to are millennials, or were considered millennials at some point in the 5,000 times the generational definition has been changed, then I suppose yes it could vaguely be construed as a tiny slice of a particular sect of millennial culture.

Having said that, there are millennials who are grandparents, and I would bet my last buck that there are some who are great-grandparents (or soon to be) at this point. There are millennials still working on their secondary education, living with roommies, and never even been on a date, basically living a lifestyle and culture not much different than people considered Gen Z. The overwhelming majority of us have never experienced anything like the scenario in that post, so from that perspective, I’d say, no it’s not something specifically tied to “millennial culture”.

Great grand parents who are at maximum 45 years old? So they had kids at 15 and then their kids had kids at 15 who are having kids right now? I mean yeah that could happen. Seems like an extreme outlier but I wouldn’t bet against it.