Running mod 4.06.8 on a 2.7.2 patch. See screenshot, character has zero visible traits that would explain the fertility modifier.
Alright. So does the game dole is_barren flags by random chance, or can a bug cause a character to get this flag?
I feel like I'm getting trollfaced by the game as my close relatives just got wiped out by the plague, and if my current ruler dies heirless, the title goes to some twerp who my ruler shares a great-grandfather with.![]()
There's a couple causes. Serious illness for example can cause temporary, or even permanent, infertility, one can be born with it, the mother might become barren after a bad birth, etc.
Judging by your scenario it might actually be the former case of sickness, assuming you too caught it but survived, and just terrible luck. You'd have to check the save for the character_modifier "infertile" or "barren" to be sure of that much.
Just get a lusty wife, do your best to ensure she has plenty of oppertunities for affairs (invite lusty men to court, avoid having a high opinion of her), and then just refuse to believe that any kids she makes are not yours.
It's not an ethical method of line continuation, but needs must.
An emergency conversion to Cathar or Bogomilist can work just as well. They have the ability to outright adopt kids to be their heirs!