Biological factors refer to the physical and genetic characteristics that influence an individual's health and behavior. These factors include genetics, hormones, and brain chemistry, which can affect everything from mood to susceptibility to diseases. For example, certain genetic disorders can be inherited from parents, impacting an individual's overall health. Additionally, biological factors can interact with environmental influences, shaping how a person develops and functions. Nutrition, exercise, and exposure to toxins can all play a role in determining health outcomes. Understanding these factors is essential for fields like medicine and psychology, as they help explain variations in health and behavior among individuals.