Genealogy

My mother was giggling incontrollably.
"What?" I asked my father, confused. "So your mother's father was a friend of your father's father, that's why your father married his wife's younger sister (my grand mother) when she passed away? "
I also learned that my great-grand father had a first official wife from Huê and a concubine beside my great-grand mother, who was from Saigon. I had never heard about that first wife.
"And I gather that my great-grand mother was a beautiful woman, seeing that her son was a very handsome man...?"
"Yes" my father replied. And it was so that on his official duties, he would go out with the second wife and never with the first one who was not blessed with good looks." 
It's so nice to have a large family...