Born into a gang of criminals, Jack's upbringing was that the gang was family to him and he called most of them his aunts and uncles. Even when he was only four years old, Jack could already read and write. He even learned how to fish through Arthur Morgan. The death of his family and the decline of the Marston ranch, all happening in a very short amount of time, greatly darkened Jack's personality. His grief and loneliness appear to have developed a severe case of depression and self-loathing. 