I’m not entirely sure, but I think it depends on the type of cancer. I presume you would be at a higher risk of getting cancer if a family member had it than if a family member didn’t have it. Maybe Katy can give some more information on this?
From what I know about it, it is age dependent sometimes. A doctor told me that they think that below the age of 40 if someone contracts cancer (it does dependent on the type) that is more likely to have been hereditary and therefore when it comes to family history they are interested. If they are over the age of 40 then it was more likely to have been caused by environmental factors, and therefore family members shouldn’t be at risk.
Was there a particular cancer you wanted to know more about?