Epigenetics

Epigenetic research shows how things like diet and health can significantly affect which genes are expressed. Scientists think that it is the epigenetic rather than the genetic makeup of people that causes disease. Basically how we look after ourselves can significantly affect the likelihood that we get ill and can also affect the genetic expression of our children.

Epigenetic activation is caused by DNA methylation and histone modification, both of which serve to regulate gene expression without altering the underlying DNA sequence


http://www.pbs.org/wgbh/nova/body/epigenetics.html