My husband and I had read this book just before getting married. "Personality Plus" was very helpful for both of us. This book describes four basic personality types people have. As you read through their distinguishing traits, you are very likely to recognize yourself as one of them. The book also has a questionnaire you can fill out that will help you build your own personality profile. I turned out to be a Melancholy - the quiet and thoughtful type that prefers books to socializing. My husband scored the biggest points as a Choleric - determined, driven, hard-working. Each personality has its own pluses and minuses; understanding them in yourself helps to improve, and recognizing them in others helps to understand why people are the way they are and how to deal with it.
I think this book is very valuable for spouses, I would recommend to read it together, like we did. It is probably even more valuable for parents. Understanding and accepting your children's personality type will save some frustration.