In The Glass Menagerie, duty and responsibility largely arise from family. The play examines the conflict between one’s obligations and one’s real desires, suggesting that being true to one may necessitate abandonment of the other. We also see that duties are gender specific, and arise largely from the expectations of societal norms.
Amanda's expectations of Tom are unfair, because she puts all the familial responsibility on his shoulders.
Although Amanda demands a lot of Tom; her expectations of Laura are more unreasonable.