diathesis-stress hypothesis

n. A hypothesis about the cause of certain disorders that argues that specific genetic factors predispose an individual to a certain disorder, but that sufficient environmental stress factors must be triggered in order for the potential risk to manifest itself. For example, research indicates that genes influence the risk for schizophrenia, creating a diathesis. However, in some identical twins only one twin develops schizophrenia and the other does not. Because identical twins possess identical genes, some nongenetic factor, or stress, must play a role in the development of the disease.

- TJM