I do regular runs of the game, I especially like starting on very difficult tiles (desert, ice desert...).
Maybe I'm just not lucky, but sometimes I wait a very long time before unlocking the marvel (with the "Belief in the afterlife" trait). Even if my civilization is going very well (everybody happy at 200%, food, clothes and shelter for everyone, etc).
I know that those traits come at random, but are there things that make it slower or faster? My "culture" score is already high (I have seen somewhere that it helps, since traits "consume" culture), but apart from that?
Is there something with the children working and "becoming less educated"? I do that at the beginning of the civilization (to survive), but only for the first years and concerns (supposedly) a couple kids, not my entire population...
Any ideas on that? Did you notice the same?