In "Marigolds" by Eugenia Collier, how does Lizabeth's adolescence affect her decisions and actions in the story?

In the story, Lizabeth's adolescence is a major motivating factor in her behavior. We are told how Lizabeth feels from the very beginning of the story. The narrator (Lizabeth) takes us back to that fateful summer, when she was fourteen years old and "more woman than child." Although Lizabeth felt superior to her then eleven-year-old brother, Joey, she privately nursed lingering doubts about her place in life.
Lizabeth and Joey were the only children living at home at the time. The older ones had either married or moved to the city for employment. Lizabeth reveals that the two youngest children were living with relatives. During that awkward summer, Lizabeth's sense of security was devastated by a change in the family's status quo. Her father was unemployed and had few prospects for finding gainful work. Meanwhile, her mother, "small and soft," was suddenly thrust into the role of family breadwinner.
Lizabeth felt bewildered and frightened by the changes. She recalls hearing her father cry and admits that she had "never heard a man cry before" and, at the time, "did not know men ever cried." In Lizabeth's case, the upheaval of family life (occasioned by economic circumstances) added to the turmoil of adolescence.

Where did I fit into this crazy picture? I do not now remember my thoughts, only a feeling of great bewilderment and fear.

In that light, Lizabeth's actions can be understood from the prism of her adolescent consciousness. We are told that Lizabeth went on to destroy all of Miss Lottie's marigolds. We also learn that Lizabeth did not realize the import of her actions until after she glimpsed the sorrow on the old woman's face. It was at that moment that Lizabeth lost her innocence forever. She gained compassion for others when she lost the naivety of childhood.
The original question is, How does Lizabeth's adolescence affect her decisions and actions in the story?
When Lizabeth destroyed Miss Lottie's marigolds, she was motivated by pure emotion. Her adolescent mind took center stage. Scientists tell us that the prefrontal cortex is less developed in the adolescent than in the adult. What does the prefrontal cortex do? First, it is the decision-making center of our brain. The prefrontal cortex processes how we make decisions and how we weigh the present and future consequences of our actions.
In other words, the prefrontal cortex is all about rational decision-making. You can read more about the prefrontal cortex from the two links below.
In Lizabeth's case, she acted out of her rage, grief, and fear. She was at an extremely vulnerable period in her life. Her father was out of work, and her mother was suddenly thrust into the role of family breadwinner. At the time, Lizabeth also felt abandoned. Her mother had little time for her, and her father was incapacitated by his own grief.
Scientists tell us that the amygdala is better developed than the prefrontal cortex in teenage brains. So, what does the amygdala control? It is in charge of the processing of emotions. When we act on our gut instinct, we're relying on our amygdala to guide us. You can read more about the amygdala and how the teen brain works from the link below.
In the story, Lizabeth acted out of emotion and instinct. In other words, we can partially blame biology for her erratic and emotion-driven actions. Scientists would say that her underdeveloped prefrontal cortex caused her to throw all caution to the wind and destroy Miss Lottie's marigolds. In the story, Lizabeth admits that adolescent angst was behind her thoughtless and cruel actions those many years ago:

The years have put words to the things I knew in that moment, and as I look back upon it, I know that that moment marked the end of innocence. Innocence involves an unseeing acceptance of things at face value, an ignorance of the area below the surface. In that humiliating moment I looked beyond myself and into the depths of another person. This was the beginning of compassion, and one cannot have both compassion and innocence.
https://science.howstuffworks.com/life/inside-the-mind/human-brain/teenage-brain1.htm

https://www.pbs.org/wgbh/pages/frontline/shows/teenbrain/work/onereason.html