What can we change about the given genetic material? How the environment and than what we do to our bodies influence us and even our inheritors? There is a network of chemical switches that sit on our DNA, turning genes off and on!

Epigenetics

In biology, and specifically genetics, epigenetics is the study of inherited changes in phenotype (appearance) or gene expression caused by mechanisms other than changes in the underlying DNA sequence, hence the name epi- (Greek: επί- over, above) -genetics. These changes may remain through cell divisions for the remainder of the cell's life and may also last for multiple generations. However, there is no change in the underlying DNA sequence of the organism;   instead, non-genetic factors cause the organism's genes to behave (or "express themselves") differently.

Mark Mehler, professor of Neurology at Albert Einstein College of Medicine:

We're in the midst of probably the biggest revolution in biology, which is going to forever transform the way we understand genetics, environment, the way the two interact, and what causes disease. It's another level of biology, which for the first time really is up to the task of explaining the biological complexity of life. ... But, in fact, the human genome project was just the beginning. 

Marcus Pembrey of the Institute of Child Health at University College London, a co-investigator in the Swedish study:

You live your life as a sort of ... guardian of your genome. It seems to me you've got to be careful of it because it's not just you. You can't be selfish ... you can't say, 'Well, I'll smoke' or 'I'll do whatever it is because I'm prepared to die early.' You're also looking after it for your children and grandchildren... Epigenetics is changing the way we think about inheritance forever.

Michael Skinner, Washington State University:

In fact, we found out that the human genome is probably not as complex and doesn't have as many genes as plants do. So that, then, made us really question, "Well, if the genome has less genes in this species versus this species, and we're more complex potentially, what's going on here?"

Randy Jirtle, Duke University Medical Center:

Epigenetics literally translates into just meaning above the genome. So if you would think, for example, of the genome as being like a computer, the hardware of a computer, the epigenome would be like the software that tells the computer when to work, how to work, and how much. ... We've got to get people thinking more about what they do. They have a responsibility for their epigenome. Their genome they inherit. But their epigenome, they potentially can alter, and particularly that of their children. And that brings in responsibility, but it also brings in hope. You're not necessarily stuck with this. You can alter this.

Jean-Pierre Issa, M.D. Anderson Cancer Center:

Perhaps the best example of an epigenetic phenomenon... you're actually looking at it. You see, skin and eyes and teeth and hair and organs all have exactly the same DNA. You cannot genetically tell my skin from my eyes or my teeth, yet you couldn't really imagine that these are the same tissues.

Moshe Szyf, McGill University:

We have this very, very static genome, very hard to change. It could be only changed by really dramatic things like nuclear explosions or, you know, hundreds of thousands of years of evolution. On the other hand, we have the dynamic environment that changes all the time. And so what there is here is an interface between the highly dynamic world around us and the highly static genome that we have. Epigenome is an in-between creature, built in a way, to respond to changes around us.

Andrew P. Feinberg, Johns Hopkins University:

It's a little bit like the dark matter of the universe. I mean, we know it's there, we know it's terribly important, but we don't really know all that much about how that symphony gets played out.

Walter Kaufmann, Kennedy Krieger Institute:

We know environmental stimulation, sensory stimulation, auditory, visual stimulation, have an impact on brain development and brain function. And this impact we know now is mediated, at least in part, by epigenetic mechanisms.

The Ghost in your Genes

BBC Horizon Documentary

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