Mental illness is defined as a biological disorder that disrupts a person's thinking, feelings, mood, and ability to relate to others. It can be caused by genetic traits inherited from families, imbalances of chemicals in the body, patterns of cell communication, lifestyle factors like poor diet and substance abuse, and environmental exposures to trauma, violence, abuse or neglect. Risk factors for mental illness include antisocial attitudes, lack of education, poor employment history, lack of social and leisure activities, substance abuse, antisocial peers, and family or marital issues.