They certainly know about his family and his close friends.
"There are things I don't want to know about my family."
Actually, it's very easy - write down everything you know about yourself and your family!
In reality, little is known about his family and early life.
So he knew things about her own family which she had not troubled to discover.
I've known about your family for several years now.
I only knew about his family from what he said.
She was the youngest of four children, but little else is known about her family or early childhood.
"Now there's nothing the people of this state don't know about me or my family."
That's how she knew so much about you and your family in Tours that night.