Jem has been greatly influenced by his father, Atticus. Jem tends to think things through, especially as he gets older. Atticus advised his children not to judge a person until you've walked around in their skin. In other words, know the person's background to understand his actions. At the beginning of the book, Jem was immature and reacted before thinking sometimes. An example of this is when Dill dared him to run up to the Radley house and touch it. Jem's action could have gotten him killed, but I think Nathan Radley shot to scare, not kill. After that, Jem's actions and his explanations to Scout seem more thought out and rational. Scout was the hot-headed, impulsive one, while Jem was more thoughtful, probably because of his age.