Though there are several reasons for including family data in a medical history, such information often turns out to be irrelevant. Still, family information may be made relevant by recording certain minimal data about first-degree relatives; by asking five questions designed to survey the family for occurrence of the same problem, related problems, clearly heritable traits, unusual conditions, and consanguinity; and by contructing a pedigree. The first step applies to every history; the second step to most; the third to only a few.
Juberg RC. Making the Family History Relevant. JAMA. 1972;220(1):122-123. doi:10.1001/jama.1972.03200010106021