Saw a great program a few years ago on Epigenetics on a NOVA program called Ghost in Your Genes.

pbs.org

Full transcript is here:

pbs.org

NARRATOR: Imagine sharing life with a person who seems to be you. Created from the same fertilized egg, you share exactly the same genes. So profound is their influence, everything about you appears the same: the spaces between your teeth, the way you laugh, your body language. You are, in a word, identical. Or are you?

SUSAN: As infants, they were very much alike. Their physical similarities are obvious. And all their physical milestones happened at the same time. But functioning today, for Jenna and Bridget…they’re completely different.

Jenna is enthusiastic, productive. Jenna’s going to college. She talks about it all the time now. Bridget is essentially non-verbal. She doesn’t have purposeful conversational speech. And there’s very unusual behavior. For example, she likes to spit on monitors and then rubs it in. I don’t know why, but that’s what she does.

How? How could these guys be identical and so, on such a different level, functioning-wise?

NARRATOR: So if genes don’t tell the whole story of who we are, then what does?

Scientists suspect the answer lies in a vast chemical network within our cells that controls our genes, turning them on and off.

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.

MARK MEHLER (Albert Einstein College of Medicine): We’re in the midst of probably the biggest revolution in biology that is going to forever transform the way we understand genetics, environment, the way the two interact, 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.

NARRATOR: Ghost in Your Genes, up next on NOVA.