Cancer is a genetic disease caused by certain changes to genes that control the way our cells function, especially how they grow and divide. Certain gene changes can cause cells to evade normal growth controls and become cancer. For example, some cancer-causing gene changes increase production of a protein that makes cells grow. Others result in the production of a misshapen and nonfunctional form of a protein that normally repairs cellular damage. Genetic changes that promote cancer can be inherited from our parents if the changes are present in germ cells, which are the reproductive cells of the body eggs and sperm. Such changes, called germline changes, are found in every cell of the offspring.