100% cancers are caused by certain changes to genes. An abnormal change in a gene is called a mutation which can affect how it functions. Gene mutations can be either inherited or acquired. An inherited gene mutation is passed through generations. Individuals with as family history of cancer may have an increased risk of cancer. An acquired (somatic) mutation does not come from a parent, but is acquired some time later. These changes can be caused by environmental factors. Acquired mutations can not be passed to the next generation.