I've accepted that it'll probably never happen for me
I haven't settled down and had a family or anything like that, so I haven't even got that to provide an illusion of adulthood. I always imagined that I'd reach a point in life where it would seem like the appropriate time for that sort of thing, but so far I haven't felt that way. I was talking about this with my dad and sister a while back and my dad said "kids just sort of happen, you know?" and we both disagreed (my sister also doesn't have her own family). Nearly all of my friends have kids, and for them it did seem to just happen as well. I probably overthink the whole thing a bit, but then having children isn't a priority for me at all so there's no reason to try to change really.