1. During which period in history did Mary Shelley write Frankenstein, and what were some of its social behavior codes that clashed with her personal life?

Victorianism.

Social codes during this period included:

Getting married and having children. Morality.

This was the model that was imposed by Queen Victoria herself, in her portraits she is always seen surrounded by her happy family. Mary Wollstonecraft Shelley never had a happy family, she runaway with Percy Shelley when she was a teenager, he was married to someone else at that time. Her father didn't speak to her for several years because of this. In fact, Mary and Percy married many years later (against the convention of that time), after losing and baby and experiencing the death of their baby girl (At that time, people had to marry before having children). Only one son survided, and Percy died when Mary was still very young. So they could never be (and they never wanted to be) the big happy family that Victorianism had as its model.

Women were below men

This is why they didn't publish books and if they did they would do it anonymously. Mary Shelley belonged to a family that had already broken these codes since her late mother was one of the first feminists of the world. It should also be noted, that most women didn't receive formal education, this was the case of Mary Shelley. All the same, Mary continue to write and after some years she did publish her works under her own name.