Every so often I becomes suspicious that my wife (or one of my lovers) is cheating on me and I have the option to investigate.
However I don't see any reason why I would want to know if they are cheating on me.
If my wife is fertile it pretty much means that I want kids (if I didn't I would have married someone infertile in the first place). And since my wife has not given birth yet when the event occurs I can't even know if the kid has good traits or not.
It seems that the best option is always to put my fingers in my ears and pretend the kid is mine so that I can expand my dynasty or possibly get a good heir.
Is there any reason I could have to want investigate my wife for infidelity?
Best Answer
For single player games there is only one reason to do so.
Bastards who are identified as such are born with the Bastard trait, making them unable to inherit from either parent, and preventing them from passing on either parent's dynasty. (see Bastard).
So, it is a way to control your inheritance. Having many sons in an agnatic-gavelkind realm is bad, but finding out that one is a bastard, you can easily kick him from sucession.
For multiplayer games, there is a second possibility to utilize this. If your bastard-sons real father/mother is your liege, the liege has the possibility to legatimize the child for little cost (20 piety). This would change the childs dynasty from the vassal ones (yours) to the dynasty of your liege, effectively bearing a great danger to your sucession.