I guess it is a superposition of both.

Current stage in life setting the general tone/direction (edgy young, sense-searching youth, family-focused middle age, backwards-directed old).

And the time of upbringing determines the content to focus on and the specific type of execution (e.g. when reaching the "old" group some time soon, I will probably bitch about completely other things than current boomers and my memes will be more high-quality due to better skills, but I won't be doing TikToks...)