Comment by Hwmoq on Return of the Legendary Spear Knight - Chapter 50

It's the king.

Most likely, since I've seen some spoilers that the dukes legitimate isn't Babel. We also saw how the duchess talks with the knight.

Yes, he's the father. I think the Duke even figured it out. That's why he left and took the other wife with him.

Babel's mother's brother

Nope the king is his father

So incest? The king and his sister which is babels mother?