Surprised to be playing as the bastard of the the Sheik that I had killed.

So I am playing as Umayyad spain. I had some kind of struggle with "Nick the Lecher" who owned two counties and was set to inherit more soon that may have become a rival. After a few attempts his wife who actually liked him better than she liked me killed him for 600 gold. (I was glad it wasn't a ruse). However Nick seems to have the last laugh, as my successor is his bastard. I only found out when I had to edit the savegame because my successor apparently moved his little counties capital when I wasn't yet playing as him. In a sense I have lost the game... my DNA line is no longer in power. I also only recently made this particular son my successor because he had slightly better steward score than my other son.