These reactions influence how our genetic code is expressed: how each gene is strengthened or weakened, even turned on or off, to build our bones, brains and all the other parts of our bodies.

But because the DNA code itself remained unchanged, Morris's team suggest that the changes in gene expression are epigenetic.

Once we begin to pay attention to the reasons that a gene might express itself, we may be able to prevent that gene from releasing its code for illness.