Why di I need a family medical history?

Heredity. Heredity is very important not only to know wether you are likely to develop a disease but how aggresive will it be.
DNA+. You are a genetic product of two lines of genetics. Some diseases exhibit themselves probably when exposed to certain "carcinogens" in our everyday environment. We really don't know what does turn certain cancers on, in some ways our own body kills off cancer cells regularly, sometimes this system fails; these cancer cells continue to multiply. I try to discover through the history possiblity .