Generally speaking cancers are caused by DNA mutations. Most of time these mutations are not hereditary. It means that
they occur during our life after birth. The consequence is that the older we are the greater the chance to have a cancer. But sometimes it can be inherited. For breast cancer for instance mutations are known on brca1 and brca2 genes which are hereditary. However they concern only 5 % of breast cancers. Usually for brca1 and brca2 hereditary mutations there is an abnormal number of breast cancers in a family and doctors specialized in genetic are then looking for the presence of these mutations.
You can’t pass it down. It is something that develops from stressers be it through toxins or actual mental stress. A lot of "auto-immune" diseases and issues are brought on by stress believe it or not. There has to be more studies done on it, but many scientists are now saying poor body image can bring on autoimmune disorders.