be (all) brothers/sisters under the skin

be (all) brothers/sisters under the skin

Said of people who have thoughts or feelings in common, despite other obvious differences between them. As much as you dislike your chatty new co-worker, she's as nervous and insecure as you are—you're really sisters under the skin.
See also: brother, sister, skin

be (all) brothers/sisters under the ˈskin

be men/women with similar feelings, in spite of outside appearances, position, etc: Actors and politicians are brothers under the skin. They both need public approval.
See also: brother, sister, skin