Scientists have unveiled the first detailed map of the epigenome, the network of chemical switches that regulates activation of human genes, according to a study to be published Thursday. The decoding of the human genome nearly a decade ago laid bare the building blocks of life, fuelling expectations that science would swiftly uncover the links between genes and disease.
But the connections turned out to be more complicated than imagined. What emerged was an additional layer of genetic signalling - known as epigenetics, literally "on top of" genes - that remains poorly understood. Scientists were also startled to discover that environmentally-caused changes in these chemical triggers could be inherited from one generation to another. What we eat and the toxins to which we are exposed, in other words, can lead to heritable modifications in how and when genes are silenced or activated.