Epigenetics: Is a way of influencing how our genome is regulated without the DNA code itself being changed. Epigenetics can determine when genes are turned on and off (also referred to as gene expression), and which proteins are produced as a result. It can even control the structure of the genome, relaxing the tightly packed chromosomes to allow the factors which control gene expression access to the genes within.
One example of an epigenetic modification is methylation, which is associated with switching genes off. Here, a chemical called a methyl group attaches to a region near the start of a gene and prevents it from being switched on.
Lynch syndrome also illustrates the significance of the epigenetic component in cancer development. Inactivation of tumor suppressor genes by epigenetic mechanisms is an acquired property of many tumors developing in Lynch syndrome.
https://www.genomicseducation.hee.nhs.uk/education/core-concepts/what-is-epigenetics/
Lynch Syndrome Ireland 