not (one's) brother's keeper(redirected from not someone's brother's keeper)
not (one's) brother's keeper
A rude or flippant way to say that one is not be responsible for another person's actions, behavior, or whereabouts. Of course I'm disappointed that Travis got arrested again, but I'm not my brother's keeper. How should I know where Mary is? I'm not my brother's keeper.
not your brother's keeper
You can say that you are not your brother's keeper to indicate that you do not accept responsibility for other people in any way. Part of me wants to help him, but part of me realizes I can't be my brother's keeper. Note: These expressions come from a story in the Bible. Cain has killed his brother, Abel, but tries to deny it. `And the Lord said unto Cain, Where is Abel thy brother? And he said, I know not: Am I my brother's keeper?' (Genesis 4:9)