In The Handmaid's Tale how did Serena Joy's past experiences shape her?
In the past, Serena Joy had been a singer. She had been small, angelic, and prone to crying and getting very emotional when she sang, especially religious songs about God. She was also an activist; she used her celebrity to push the causes that the new Gideon society would eventually espouse: chastity, virtue, homemakers. She was fervent and believed intensely in those causes.
Because of her fervent beliefs about virtue and religion, she was a perfect fit for the new society that was imposed upon America. Since we don't know her inner thoughts, we don't know if she is happy living the way that she does. She certainly doesn't seem happy; she is stern, unhealthy, and desperate for a child. That assessment is rather biased though, since we only see her through the lens of Offred, with whom Serena doesn't have a good relationship. Her days are filled with almost nothing except gardening though, and she doesn't seem to be filled with radiant joy. She got what she believed in, and Offred herself wonders if she found it to be everything that she thought it would be.
Her past experiences shaped her into the perfect vessel for the ideologies of the Gideon society. She was a good candidate for a high-ranking Wife, one who actually believed in the philosophies that were being enforced. Her devout, religious nature and activism for modesty and virtue helped her to fit in seamlessly in the new world. I hope that those thoughts helped; good luck!