It's often easier for us to think that other people's behavior is due to their character, as opposed to their circumstances or experiences. Social scientists have named this tendency the fundamental attribution error. We're less likely to make this error when it comes to our own behavior, because we know what motivates us to do a particular thing. How do you explain why people do what they do? Are your explanations different for yourself?
Further Reading
The mistake we all make... and the simple experiment that reveals it. (article)
What kind of person steals their co-workers' lunch? (article)
