Genetic knowledge provides us not only with a molecular explanation for various behaviors, but also with the realization that we all carry vulnerabilities to medical and psychiatric disorders. Genes are segments of DNA that consist of codes for proteins the body makes and uses to run itself on a daily basis. Many of those proteins create physical characteristics (eg, eye color). Other genes contain the instructions for proteins that function as chemical messengers in the body. Some hormones are chemical messengers that can have powerful effects on emotions. Hormones are molecules that fit into specific receptor sites on living tissues, and that cause those tissues to respond in a certain way. Many hormones travel by way of the blood stream a great distance from where they are manufactured to the target organ they affect. However, other hormones often are manufactured and stored in the tissue where they are later used. A common hormone with which many people are familiar is epinephrine (adrenaline) – the “fight-or-flight” hormone. When a person is frightened, scared, or severely startled, this hormone is released by
