Hello Daud,

Just for the sake of thoroughness (and humor), one could literally have skeletons in their closet. Not necessarily human ones; maybe cat skeletons, for example. They could be decorative or real. Perhaps from a high school project.

Take care,

Chase

You're right! Not necessarily. Depends on what or whose skeleton...

Hahahaah you're right sir,, but that doesn't necessarily mean that the person is hiding a big secret.

It's a phrase ; it means an obviously an irreproachable person or a guilty secret

in the family that is waiting to be reveal.

Yes, it’s an idiom. It means secrets or shameful things that one doesn’t want others to know about.