So I was first interested in this question because I was playing some CK2 and in the game there are a considerable number of ruler characters that have illegitimate children from their mistresses. I understand that illegitimate children have existed in history and have at certain times played important events in history, such as William The Bastard/The Conqueror, however I'd like to know just how common it was for rulers to have illegitimate children.
To clarify I'm asking about rulers not only from one part of the world such as Europe but also from other areas and cultures too as I'd also like to know if there was any difference in who was counted as illegitimate between different cultures. I'd also like to know if possible about how common it was for a peasant to have illegitimate children so to know whether illegitimate children was a 'title' (if you could call it that) that was only placed on noble families
Source: reddit post