This famous phrase became an idiom. As such, it has a meaning that extends beyond the literal, word-for-word translation.
Literal meaning: ‘ha’ in English is the definite article ‘the.’ ‘Sho•mer’ means ‘keeper’. A•chi means ‘my brother.’ ‘A•no•chi’ means ‘I.’
This phrase was said by Cain to God after he murdered Abel.
“And the Lord said to Cain, ‘Where is Abel your brother?’ And he said, ‘I know not; Am I my brother’s keeper?’”
Extended meaning: Because this phrase has become an idiom, it may be extended to express denial of responsibility where one is accused or perceived as being responsible for the actions of another person.