How does The Outsiders suggest the individual identity of a person is determined by their external influences? How do the techniques and conventions of the novel reinforce this idea?
The statement "the individual identity of a person is determined by their external influences" is certainly an opinion-based statement; evidence from the text can be used to agree or disagree with this idea.
Conventions and techniques refer to literary techniques and conventions used by the author, such as foreshadowing, figurative language, character development, flashback, flashforward, backstory, unreliable narrator, and more.
I would suggest you choose a position (is a person's identity in fact determined by external circumstances or not?) and back it up with evidence from the text, which would include the literary techniques of the author. For example, if one were to argue that a person's identity is determined by his/her external circumstances, using the example of Darry would work well to support this argument. Darry doesn't finish high school and becomes the sole breadwinner of the household after his parents' deaths. He had a lot of potential as an athlete and was smart, but his external circumstances changed the course of his life and subsequently, his identity. His former football buddies saw him as an outsider after he dropped out of high school.
If one wanted to argue that a person's identity is not determined by his/her external circumstances, he/she could use the example of Ponyboy. Ponyboy is a gifted writer, academically driven, and not given to violence. He does not fit the stereotype of a typical greaser. He has integrity of character and a moral fortitude that others don't have. A literary technique that supports this argument is the full-circle ending. The first and last lines of the book are: "When I stepped out into the bright light of the sunlight from the darkness of the movie house, I had only two things on my mind: Paul Newman and a ride home." This full circle ending suggests that Ponyboy does not change despite the circumstances of the novel. This is echoed in Johnny's advice to Ponyboy to "stay golden." Despite the violence and horror around him, Ponyboy remains true to himself. His identity is rooted in something deeper than his external circumstances.
Also consider the use of flashback, foreshadowing, and figurative language to reference the techniques used by the author when writing this essay.