Molecular insight into our own DNA is now possible, a field called personal genomics. Such approaches can let us know when we might have cancer-causing alterations in our genes. Well-known examples are the melanoma oncogene BRAF kinase, the breast cancer gene BRCA1 and the prostate specific antigen PSA.

But there is more to cancer and other diseases than our genes. In addition to the DNA code, there is a hidden layer of regulation controlling the activity of genes – while not changing the DNA itself. This field, called epigenetics, is the study of how genes are regulated to express themselves, even though they rely on the same genetic information. A gene is still a gene, but it responds differently to many facets of its chemical environment.