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general::
Phrase(s): be one’s brother’s keeper
to be responsible for someone else. (Used of others besides just real brothers.) • I can’t force these kids to go to school and get an education so they can get jobs. I am not my brother’s keeper. • You can’t expect me to be my brother’s keeper. Each of us should be responsible for himself!
McGrawhill's American Idioms And Phrasal Verbs