Final answer:
The Diathesis-Stress Theory states that mental and physical disorders develop from a genetic or biological predisposition combined with stressful conditions. It explains that individuals may have a genetic vulnerability, but it is the presence of stressful life events that triggers or facilitates the development of the disorder.
Step-by-step explanation:
The theory that mental and physical disorders develop from a genetic or biological predisposition for that illness (diathesis) combined with stressful conditions that play a precipitating or facilitating role is known as the Diathesis-Stress Theory. According to this theory, individuals may have a genetic vulnerability or predisposition for a certain disorder, but it is the presence of stressful life events that triggers or facilitates the development of the disorder. For example, someone with a genetic predisposition for depression may only develop the disorder if they experience significant stressors, such as loss of a loved one or job-related difficulties.