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The gene scene

Are babies being genetically modified before they are born? Research suggests they are.

Scientific scandal erupted in 1920s Vienna over a type of toad. Midwife toads live on land, but biologist Paul Kammerer forced the toads in his lab to live and breed in water. A few generations in, the toads developed black foot pads - an environmental adaptation common to water-dwelling toads.

Kammerer's results seemed to support the theory that an organism could pass on traits it had developed during its lifetime. But in 1926, a reptile specialist claimed the black pads on Kammerer's last surviving toad were the result not of evolutionary adaptations but of injections of Indian ink.

Kammerer may have had nothing to do with the alleged fraud: it has been suggested a Nazi sympathiser tampered with the toad to discredit Kammerer, a prominent socialist and pacifist. Nonetheless, Kammerer committed suicide six weeks later.

However, 2009 may be the year of Kammerer's rehabilitation. After re-examining the toad data, evolutionary development biologist Alexander Vargas believes Kammerer inadvertently discovered how DNA modifications can be passed on to subsequent generations. Rather than being forever associated with scientific fraud, Kammerer may come to be known as the father of epigenetics.

Epigenetics is a relatively new field of science looking at gene modification. One of its most intriguing areas of study is whether environmental factors can modify genes during a baby's early development in the womb. Factors such as diet or stress within just a few days of conception may be able to trigger a predisposition to health problems such as obesity, cancer, diabetes or heart disease.

We are all dealt a fixed hand of cards - the genes we inherit from our parents. But our genetic blueprint is not the end of the story: our genes' DNA is modified before and after conception to change the way the genes behave.

The fate of developing cells is determined by which genes are switched off or on. Epigeneticists are particularly interested in methylation, a process that can turn off or "silence" the way a gene expresses itself. If a gene that regulates cell growth is silenced, for example, cells may continue to grow, causing cancer.

Your nose and your eyeball are genetically identical, yet look different. Epigenetic signals appear to be the master controllers in determining how organs and tissues are formed, but it's uncertain how open to change this process is.

The most exciting discoveries in epigenetics have been made in mutant lab mice. When mice have been fed modest amounts of extra vitamins during pregnancy, the mutation has been neutralised by methylation. As a result, fat yellow mice have produced babies that grow up lean, healthy and brown.

Some evidence suggests that women who eat poorly in early pregnancy may have children with health problems. A study in the Netherlands found that people conceived near the end of World War II, when the country was experiencing a famine, have an increased risk of cardiovascular disease. But even the Dutch study makes "a truckload of assumptions", says Professor Ian Morison, head of pathology at the University of Otago's Dunedin School of Medicine and project leader at the National Research Centre for Growth and Development. Another possible explanation is that a fetus growing during food shortages may develop smaller kidneys, which increases the chances of high blood pressure.

Morison has been working in epigenetics since 1993, but remains sceptical about some claims made for the field. Although there are proven links between epigenetics and cancer, the connection between epigenetics and development is less clear.

One intriguing new area of research is the differences found in children conceived through IVF. These children tend to be taller and leaner, to have better lipid profiles - which means a lower risk of heart disease - and to be more likely to suffer from two rare epigenetic disorders: Beckwith-Wiedemann syndrome and Angelman syndrome. The differences suggest that IVF children are programmed differently during their first few days of life in a petri dish.

Morison's next project will involve using powerful new DNA sequencing technology to try to catalogue the genetic differences between people and then look at the consequences of those differences, such as obesity or premature birth. Other researchers are investigating foods that may counter unwanted epigenetic influences. "I have found epigenetics frustrating because so many questions remain unanswered, " says Morison. "But it's an exciting area to work in, because it has so much potential. If it's real - if your early development in the uterus really does prepare you for the rest of your life - the implications are huge."