Not genes determine the likelihood of developing cancer in humans. In most cases, lifestyle and environmental factors affect the development of cancer. Previously in the scientific world met often "bad luck hypothesis". According to it, mutations occur in cells randomly. This is the main factor that trigger the occurrence of tumors. Modern studies show that accidents in the development of Oncology not so much.
Smoking, drinking alcohol, air pollution, solar activity and a number of other factors that can cause cancer. Enough to abandon bad habits, to reduce the likelihood of some cancer localizations by 90%. In rare cases, lung cancer develops in non-smokers, and cirrhosis of the liver – people who have never used alcohol.
Note, some tumors arise for no apparent reason. Unclear risk factors in cancer of the blood, the example of scientists. Such a process is not controlled by the lifestyle of the person, to prevent it does not.