It's pretty unlikely now, yeah. I understand that people shouldn't have 14 kids in 100 turns, but zero kids a game kind of negates it. Maybe it should be on a sliding scale where your first child is 1/30, then 1/50, then 1/100 for subsequent kids. That'll pretty well guarantee you one child if the game goes any duration, but you will see some randomness in how many you get after that.
This sounds like a very good approach to me, even faintly realistic given the challenges of maintaining family loyalty when travel times get long enough for someone to get pregnant and give birth en route from a provincial city to the royal capital.
On the other hand, maybe the devs are puttering with some ideas about encouraging sovereigns to make their own first marriages diplomatic ones? Somewhere recently I had a game going as Procipinee and there was a magic-centered independent faction fairly close to my starting locale. Maybe the game should encourage us to think about spouse-hunting among factions like that rather than shacking up with the first opposite-sex wandering champion who comes along.