"skeleton in the cupboard" - means that there is a secret being kept "run in the family" -- there is a trait or characteristic that more than one family member has, therefore you can say that it runs in the family. Ex. Aunt Jessie and her daughter are both such talented artists. I guess it runs in the family. "your own flesh and blood" -- a family member-- usually in your immediate family. Ex. When I pass. I will be leaving my estate with my own flesh and blood. Hope this helps! =) "wear the trousers"-- if someone wears the trousers in a relationship. it means they're the boss and make most of the important decisions. Ex. Everyone knows that my mother wears the trousers in our family.

It means your mother-in-law has been around too long.

for the skeleton http://www.italki.com/answers/question/94303.htm

"to have a skeleton in the cupborad" means "a secret of one's family"