I'd try pulling simler90's core mod first. It has wide-ranging effects, possibly including adjusting the mechanism behind wish fulfillment, and its developer is still working out the finer points of the mod. That's not to say you shouldn't use it, but it would be worth testing without the mod present, particularly if you have a backup save from before this child's birth.
I play with NRaas mods and haven't ever seen this in all the years I've played. (I'd have remembered and been annoyed.) I recognize most of your other mods, and I don't believe any of them could have this effect. But you could certainly test with only NRaas mods in place as well.
The other possibility of course is that this sim is not the father of his wife's child, but I'm guessing you'd know that.
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These are my mods.
I play with NRaas mods and haven't ever seen this in all the years I've played. (I'd have remembered and been annoyed.) I recognize most of your other mods, and I don't believe any of them could have this effect. But you could certainly test with only NRaas mods in place as well.
The other possibility of course is that this sim is not the father of his wife's child, but I'm guessing you'd know that.