Human behavior is what people do and how they do it. The mental and physical responses by which such actions are expressed depend on environmental input to our sense organs. The various stimuli are coordinated and controlled by immensely complicated network of nerve impulses and by hormonal messengers. Our activities are therefore based on aspects of anatomy and physiology that we know can be affected by genes encoded proteins. It should therefore be expressed that genetic variations can lead to behavioral variations. The Psychogenetic study deals with the behavior of human beings that develops in response to interaction between inherited limitations and environmental factors. There are many causes of behavioral adaptations. In some instances for example, in certain forms of brain damage, organic cause is uncovered, in other cases undesirable present or past relationship and a combination of these factors along with a stressful environment such as death of a loved one may be implicated.