Reasearchers at Johns Hopkins studied 31 different cancer types and found that 22 of them are most likely the result of DNA mutations that happen during ordinary cell division. In other words, the cancer pretty much just happens randomly.
Most cancers–including bone cancer, ovarian cancer, pancreatic cancer, brain cancer and leukemia–are not the result of learned behaviors (drinking, smoking) or even heredity (characteristics passed to offspring from their parents through genes). Smoking-related lung cancer and skin cancer saw a stronger influence from behaviors. Dr. Bert Vogelstein of Johs Hopkins University School of Medicine co-authored the study with Christian Tomasetti, a biomathematician at Hopkins. It was published in Science. “Some tissue types give rise to human cancers millions of times more often than other tissue types,” reads the study. “The majority is due to ‘bad luck’.”