Monster plants and our father's fears in new DNA research on epigenetics

Until very recently, it seemed the overall picture of genetics was well known. DNA molecules encoded for a host of attributes that created organisms like you and me, and we essentially served as receptacles for our inherited DNA, perhaps passing them on via mixing with a sexual partner's DNA.

Darwinism ruled as the theory of evolution, and DNA was evidently the only way you could directly pass characteristics to your descendants. Ideas of naturalist Jean-Baptiste Lamarck, published in the early 19th century, had been derided and dismissed: there was no serious acceptance that changes a person makes, like a blacksmith developing powerful muscles, could be transmitted to their children.

Yet thanks to a recent flurry of research, there are indications that the true picture is more complex. This research is in a field called epigenetics, which concerns ways the DNA code is actually expressed and implemented.

Though reported findings and implications are intriguing, epigenetics is distinctly weird. Even its definition is fuzzy, and while there are strong signs epigenetic changes can be passed from one generation to another, no one can figure out just how this happens. This led to an article on the Nature website quoting William Kelly, a developmental geneticist at Emory University, in the US city of Atlanta, Georgia, who said: "Impossible things are happening every day." (Kelly was himself quoting a line from Rodgers and Hammerstein's Cinderella.)

During the 1740s, Swedish botanist Carl Linnaeus wrote of one of the apparently impossible things, after examining a specimen of common toadflax with remarkably different flowers. To him, it was a "monster", akin to a cow's calf being born with the head of a wolf. It was not until the 1990s that the mechanism for producing such a monster was discovered, as plant biologist Enrico Coen, in Norwich, Britain, found that a gene responsible for flower structure was switched off by chemicals known as methyl groups. Remarkably, too, this trait was passed through seeds to later generations.

A similar hereditary influence through an epigenetic alteration to a gene was reported in a study published last December. But this time, the gene belonged to mice, and resulted from a group of mice being sensitised to the smell of acetophenone. Firstly, when exposed to this smell, the mice were given a mild electric shock. Then, researchers assessed how anxious they became on hearing a loud noise, with and without the odour.