Genogram symbols make it easier to understand family structures, relationships, emotional dynamics, and health patterns at a glance. The most widely used genogram notation is based on the McGoldrick-Gerson-Petry format, outlined in Genograms: Assessment and Treatment, 4th edition, by Monica McGoldrick, Randy Gerson, and Sueli Petry. This guide walks you through the commonly used person symbols and relationship lines, explains how to tell similar symbols apart, and shows you how to use a legend so your genogram can be interpreted correctly.