Why does Maddie scrunch up the Twinkies' wrapper before returning to her mother's in the novel, Alone?

Maddie scrunches up the Twinkies wrapper in her pocket because her mother is often critical of her father’s parenting choices. Maddie struggles to see her parents as separate entities, rather than the married unit they were previously. As such, she feels pressure to hide parts of herself from her mother, so she does not upset her or cause more tension in their relationship.