Genes, Dreams and Reality

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no matter how much scientists learn about genes, cancer will continue to snatch away the lives of your near and dear ones. Because it has more to do with the state of your environment than your genetic makeup.

That's what a study published this fortnight on cancer says, contradicting what geneticists have long espoused: that cancer's roots lie in genes. The findings are startling. Environmental factors cause about twice as many cancers as hereditary factors. The study, which has been conducted by the Karolinska Institute in Stockholm, may also come as a respite to those who have a family history of cancer and fear that they, too, would fall victim to it. According to the study, the risk of developing breast cancer, for example, is less than nine per cent if your sister has it. For an identical twin sister, the risk is only 13 per cent. "In the current climate, there is this sense of fatalism on the part of the public with respect to genes,' says Robert Hoover of the National Cancer Institute, Rockville near Washington, usa . This fear, he says, is unfounded.

The study is, in fact, a slap in the face of the Indian medical establishment, which has for long ignored the link between cancer and a bad environment. And at a time when there is so much hype about the Human Genome Project, the study should force researchers and research institutions, not only in India, but worldwide to shift the focus of cancer research from genes to environment. "The singlemost important lesson to be learnt from this study is that there is no truth to genetic determinism, the baleful philosophy that we are only what our genes make us,' says Vidyanand Nanjundiah of the developmental biology and genetics laboratory at the Indian Institute of Science, Bangalore.
Twin theory Paul Lichtenstein, an epidemiologist at the Karolinska Institute in Stockholm, and his team, used the gold standard for such nature-nurture studies: twins. Analysing the medical histories of 89,576 identical and fraternal twins (nonidentical) from Sweden, Denmark and Finland, they compared the incidence of 28 different kinds of cancer. Identical twins have the same genes, while fraternal twins, on an average, are just 50 per cent identical in terms of their genetic makeup