Having a family history means that a person has one or more blood relatives with a certain health problem. A doctor can look at a person's family history to get some idea of the person's risk for that health problem.

Blood relatives include relatives who are alive and those who have died. They may be:

• First-degree relatives (parents, sisters, brothers, and children).
• Second-degree relatives (aunts, uncles, nieces, nephews, and grandparents).
• Third-degree relatives (first cousins).

Some family histories are stronger than others. How strong a family history is depends on:

• How closely related a person is to the relatives with the health problem.
• How many relatives had or have the health problem.