Genes carry the information that controls our appearance and how our bodies work. Genes come in pairs. We inherit one copy of each gene from our mother and the other from our father. We all have tiny differences in our genes that make us individual. For example, genes determine the colour of our eyes and hair.
Occasionally, there may be changes in genes which mean that someone is more likely to get a disease. This type of change in a gene is often called a fault or mutation. Having a faulty gene doesn’t always mean someone will develop cancer.
Changes in genes can be inherited from a parent. Changes to genes can also happen during our lifetime, and these changes aren’t inherited from our parents. They may be caused by a random mistake when a cell divides. Or they may be caused by other things, such as smoking. These are much more common causes of cancer than inherited genetic faults.