The Sims 4 baby bug ?

@kZiUnZgIaA As jpkarlsen said, most of the cheats are forbidden, especially the ones related to making babies (for obvious reasons). If you want to play the Challenge by the rules, you shouldn't even attempt to use them. That said, either I'm extremely lucky, or you are experiencing some sort of issue for real: my matriarch (with Fertility trait), had her first twins as baby 2 and 3, she's expecting her 30th baby atm and so far she had 5 pregnancies which resulted in twins. No triplets so far. So, those are my stats. I hope other players will answer to you with their own data, so you could actually see if it's just a matter of dumb luck or if somehow your game doesn't work as it should. The only thing I can add (and I don't know if this will cheer you up or freak you out) is that in this Challenge twins aren't as crucial as you seem to think. If anything, they creates a bottleneck in the flow: when is time they'll leave together, but before that they'll take two sweet spots in your household instead of just one. Every time my matriarch had twins she ended up wasting precious days of her life waiting for the blasted kids to age up, no matter how strictly I managed the whole shebang. Note to self: you can't win against maths.