Capella Human Issues Vol. 9 (4) pp. 21-34. Twin City, USA, Dec.2004 Biogenetic and environmental factors in mental health and mental disorders Authors: CC. Ajaelu; RJ Ackerman, M Marks-Frey, CE James ______________________________________________________________________________ Abstract Health encompasses mental and physical well-being, and the concept of “healthy mind in a healthy body” has been generally upheld as a resounding precept of a healthy person. It means that mental health problems affects both the mind and the body and immensely contributes to the global burden of disease and disability. In fact, the question as to the cause of mental disorders is as old as humanity itself. This article evaluates scientific investigations or studies that try to underscore the etiological basis for behavioral, emotional or mental abnormalities in human. People had believed that mental illness was caused by evil spirit, demons, ancestral spirits or individual's wickedness. Today, some researchers claimed that biological factors are precursors to mental health problems, while others claimed multiple factors. But advancement in human knowledge, in which family, twin, adoption and post-mortem studies have been used to establish that the combinations of biological, psychological and environmental factors as the major contributing factors to mental illnesses is the dominant claim. However, the theoretical and practical frameworks in which these concepts can be applied to clinical practices and evidence- based interventions are still loomed with controversies. This article explores the extent or proportion to which genetic and environmental factors play roles in the cause or exacerbate of mental health problems. That is, do mental health conditions depend on only on natural causations or a combination of many factors? Keywords: Biomedical model, Mental health, Gene, heritability Mental illness, Behavioral phenotype, Biopsychosocial model. Introduction Mental health, which includes behavioral, emotional, and cognitive well-being, is a widespread condition that could affect how individuals think, feel, and act. It also signals how we respond and handle stress, relate to others, and make choices. Mental health is important at every stage of life, from childhood and adolescence through adulthood. Over the course of individual’s life, one may experience mental health problems that could alter one’s thinking, mood, and behavior. Many factors have been discovered to contribute to mental health problems, including:  Biological factors, such as genes or brain chemistry  Life experiences, such as trauma or abuse  Family history of mental health problems  Environmental condition The term “mental health” connotes “health of the mind” as in the “health of the body.” Health the classical definition of health propounded by the World Health Organization (WHO) defined health as a state of complete physical, mental and social well-being and not merely the absence