From All Things Considered (portions of a radio news story discussing a recent Nature article challenging the conventional wisdom about genetic inheritance):

We can’t change the genes we received from our parents. But our genes are controlled by a kind of instruction manual made up of billions of chemical markers on our DNA, and those instructions can be rewritten by our circumstances — for instance, by obesity. According to the new research, they can even be passed along to children.

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The Grammar Of DNA

[Andy] Feinberg thinks he knows how this may be happening. It’s an example of an “epigenetic” effect, which is his specialty.

This field — epigenetics — is getting a lot of attention these days. It refers to things in and around our DNA, such as billions of chemical markers that attach to it. Those markers are signals that turn genes on and off. They tell the genes of a liver cell to behave differently from genes in a blood cell, for instance.

The sequence of our DNA — the human genome — has been called the book of life. Feinberg has his own metaphor for the billions of added signals that he studies. If the genetic sequence is the words of the book, the epigenome is the grammar, he says. “It helps to tell what the genes are actually supposed to do, and puts them in context.”

Our genes don’t change, or if they do, it’s a rare and random event. But the grammar of the epigenome is changing all the time. It can also be disrupted by chemicals we eat or breathe.

Apparently it can also be disrupted by obesity, because Feinberg thinks those fat dad rats in Australia created sperm cells with a different pattern of epigenetic marks on their DNA; that’s how the effect showed up in their children.

Michael Skinner at Washington State University in Pullman says epigenetic effects are swinging the pendulum of scientific attention from the genetic code back toward the impact of environment.

“I think that we’re eventually going to have sort of a merger of this,” he says. “I think that we’re going to have an appreciation of the fact that there is an environmental influence on biology that probably through more epigenetic mechanisms. There’s also a baseline genetic element of biology. And the two combined will actually give us more information about how things work.”

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The entire story, the podcast, and related links can all be found here.