Findings of a new study challenge the widespread view that cancer mutations are generally inherited or triggered by environmental factors.

In fact, American scientists have concluded that two-thirds of cancers are unavoidable even if you live a healthy life.

The researchers have discovered that cancers are caused by random mistakes in the genetic code that occur when cells divide.

Lead researcher Doctor Christian Tomasetti says it’s well known that we must avoid environmental factors such as smoking to decrease our risk of getting cancer. But he says its not as well known that each time a normal cell divides and copies its DNA to produce two new cells, it makes multiple mistakes.

The discovery helps explain why cancer often strikes people who follow all the rules of healthy living and have no family history of the disease.

You can read about the research in the journal Science.