Ronin's sire and Rumor's dam are littermates. Ronin and Ilsa share grandmothers.
I knew two guys in high school, whose mothers were sisters and fathers were brothers...
"John Smith" married "Betty Miller", and "Frank Smith" married "Kate Miller".... VERY odd!
Nope. When my biological grandmother passed away several years before I was born, my grandfather married her sister. So my grandmother is my great-aunt.