What factors influence whether a person will develop cancer?

It depends on what type of cancer it is.
Lung cancer is developed by smoking and drinking alcohol. 
Breast is usually heretic meaning that your mother or father gives it to you.

risk factor for cancer:
depending on the type:
there are a lot,, smoking can increase your chance to develop lung cancer,,
your heredity is responsible for breast cancer,, also some drugs are responsible too
moles , high climate and exposure to sun increases chance of skin cancer...