In Nectar in a Sieve, how does Rukmani break from the conventions of her culture?

Rukmani possesses are very special skill---she knows how to write. Her father felt this was a very important tool for all his children. This skill has a "double-edge" throughout the novel.  Rukmani teaches her own children this skill. For some characters, writing provides a path to knowledge and a recognition of self-worth.  For others, writing exposes the caste system inequities, anger, and discontent. At one point in the novel, Rukmani  uses her skill to help feed she and Nathan. Men look at her in disbelief. They have never seen a woman who could write anything.