That's interesting. To be fair, I've for sure been speaking from intuition alone. I'm interested to look more into the real science of it. I'm sure there is a default mode we are prone to just based on being human. My main point is that it is that our chronotype is pliable. We can shape it and mold it it we want to.
The article is suggesting there is a natural progression correlated with age, that shifts from advanced -> delayed -> back to advanced. This does not help convince me against my hypothesis that cronotype is fluid and not static.
Intuition can be valuable, but I think we should distinguish opinions from facts. This is something that affects people's health, jobs, and relationships.
Chronotype, sleep phase, and when people actually sleep are related but not the same.
The Wikipedia article and my other comments go into more detail about the research. I singled out delayed sleep phase in adolescence because it's been observed even in other species. It seems counterintuitive that this would be so consistent if there were no reason for it.
Sleep phase shifting with age doesn't make it infinitely pliable. You can influence libido, but the difference between 16 and 60 is mostly biological.
The article is suggesting there is a natural progression correlated with age, that shifts from advanced -> delayed -> back to advanced. This does not help convince me against my hypothesis that cronotype is fluid and not static.