A predisposition is a tendency to behave in a particular way or to suffer from a particular disease, usually based on the combined effects of genetic and environmental factors. It can be formal or informal, and it can be used to describe a persons behavior or a disease that they are more likely to develop.

A genetic predisposition is an increased likelihood of developing a particular disease based on a persons genetic makeup. It results from specific genetic variations that are often inherited from a parent. These genetic changes contribute to the development of a disease but do not directly cause it. Some people with a predisposing genetic variation will never get the disease while others will, even within the same family. In people with a genetic predisposition, the risk of disease can depend on multiple factors in addition to an identified genetic change. These include other genetic factors (sometimes called modifiers) as well as lifestyle and environmental factors. Diseases that are caused by a combination of factors are described as multifactorial.

Although a persons genetic makeup cannot be altered, some lifestyle and environmental modifications (such as having more frequent disease screenings and maintaining a healthy weight) may be able to reduce disease risk in people with a genetic predisposition.