Lifelines assesses health in participants, but collects information about the health of their close family members as well.
In many cases, these family members are Lifelines participants as well. This knowledge allows for a close examination of diseases that do or do not run in families.

The following subsections fall under the section Family health: Familial cancer Familial cardiovascular disease Familial chronic fatigue syndrome Familial digestive diseases Familial kidney diseases Familial mental diseases Familial musculoskeletal diseases) Familial respiratory diseases Health offspring Health parents Health siblings