Epigenetic changes

Compare it to performing exactly the same notation by different musicians: the piece is the same, but the music is different. Two people can be genetically identical, but epigenetically different.

The changes can be caused by stress or smoking, for example. These things affect your genes and can turn them on or off. When a gene is active, it can do its job and create proteins needed to perform tasks in the body. If the gene is turned off, the protein is no longer made and can no longer perform its task.

Some cancers can be caused by epigenetic changes. This is because genes are turned on that play a role in dividing cells. If too many of these cells are turned on, a tumor can form. Prader-Willi syndrome can also be caused by epigenetic disorders.