Sadrice, I believe you may be referring to Tacitus. Guy thought the various horrific martyrdoms the Romans imposed weren't harsh enough. There were plenty of other slanders thrown around as well - my favorite early slander comes from the fact that the closest emotional tie in that culture was not between husband and wife but between brother and sister - and with Christians being exhorted to love one another, this resulted in some of them, even spouses, calling each other "brother" and "sister," leading to them occasionally being accused of being an incest cult.
Anyway, yeah, pregnancy and other things required for a culture to even exist are often found in religions - and, I guess, although it's somewhat odd to us to see a child talking about it, I gather that this is somewhat of a modern thing, and that even today kids that grow up on a farm aren't exactly unknowing about the Fax of Life. I do, though, think that the occasional civilization-wide suicide cult is pretty weird, though.
Actually, I think it'd be pretty interesting if people who worshipped one god or another would have their behavior influence by such in worldgen - like, followers of a war god would more likely become soldiers, followers of a god of fish would more likely become fishermen, followers of a god of minerals would more likely become masons or something... could also make for some interesting variations between civs depending on their god list. I.e. if your civ has a god of fish you'll get more fisherdwarves or something.