Antonyms for the phrase "are one's duty to" could include "optional," "unnecessary," "unguided," "extracurricular," or "unofficial." These words suggest that there is no obligation or responsibility to perform a certain task or action. On the other hand, some antonyms that imply a sense of obligation might include "ignorance," "irresponsibility," or "neglect." These words highlight the consequences that can arise from neglecting one's duties, and imply that there are real-world repercussions for failing to live up to one's obligations. Ultimately, the choice of antonyms will depend on the specific context and intended meaning of the phrase in question.
