The Ground-breaking Book on Depression and Your DNA Feel better! The new book Silent Inheritance explains - in easy-to-read language -the concept of inherited depression. Learn how to identify the symptoms of major depression. Discover how to unlock your depression-related DNA including MTHFR and MAO-A gene variants. Find out why methylation is important to your mental health. Understand how your environment can influence your DNA. Finally, award-winning author Susan Rex Ryan shares her story and how to overcome the stigma of depression.