I'm playing as the King of Denmark, and I'm trying to marry one of my daughters to one of the siblings of the King of Sweden, Igne Stenkilsson, who's third in line of succession for Sweden. When I go arrange this marriage, I get a warning that the two characters are related, and there's a chance of them being Inbred:
While this isn't likely to be enough to stop me from arranging the marriage (it is Crusader Kings after all), I'm a little confused as to exactly how these two characters are related. I've looked through the dynasty trees, along with checking the "families" tab of their character page, and I've found nothing to suggest these two characters are related. They obviously are, otherwise the game wouldn't be giving me a warning, but I'd like to be able to figure out exactly how the characters are related. More importantly, I'd like to have a way to determine if two characters are related without needing to arrange a marriage between them.
How can I figure out how and if two characters are related?
Best Answer
Two characters are considered related for the sake of the inbreeding warning if they share a common ancestor up to their grand-grand-parents. So you should look at the character screens of the four parents and see if their parents and grandparents look similar. When there are any people listed on both sides (not necessarily in the same generation!), the game considers the characters related.
For example, the grandparents of the left person are the grand-grand parents of the right person:
In this case I am looking at the character screens of their respective mothers, but to make sure you would also need to compare the fathers side and each others father with each others mother. A convenient way to perform that comparison is to temporarily "pin" those 4 characters (icon in the upper right corner of the interaction menu). You now have them in the outliner and can switch between them with a single click.
But keep in mind that the fatherhood information you see on the character screens is the official version. When you let your spymaster spend a while "finding secrets" in various courts, you will notice just how frequent adultery is in the game. While the motherhood is reliable (at least I did not discover any "switched at birth" scenarios yet), the fatherhood information should be seen with a grain of salt. So "They are related" should be read as "They appear to be related". This of course can also mean the opposite: When two characters share a male ancestor due to an affair and your character does not know that, then the game won't give you a warning.