Is there such a thing as a human gene for bad luck? The answer is probably no, even though it does seem beyond doubt that bad luck can run in families.
"Unpleasant events tend to cluster in families", Prof Peter McGuffin, of the college of medicine at the University of Wales, told yesterday's British Association Festival of Science meeting in Cardiff. His department studies the links between a person's genetic make-up and the occurrence of mental illness.
Mental illness frequently runs in families, but so too does the tendency to pursue similar or related career paths, and this was unlikely to have any genetic component, he said. "It shows you that environment is very important."
Researchers frequently studied the occurrence of mental illness among twins, including twins separated at birth, to see whether disorders such as schizophrenia and depression arose because of nature or nurture. While schizophrenia affected only 1 per cent of the general population, 10 per cent of the relatives of a schizophrenic would also develop the disease. And there was a 50-50 chance of an identical twin of a schizophrenic also becoming one.
Various studies had convinced him that all schizophrenia was genetically-based, although the cause was likely to be a collection of genes contributing to the disease rather than a single errant gene. Recent research had involved a study of "life events, unpleasant things" and their impact on the incidence of depression among 200 families, Prof McGuffin explained.
Early work in this area had been incorrectly interpreted by the media as indicating that there was a "bad luck gene" which caused an accumulation of unpleasant and unlucky things to occur within a single family group. While this view was wrong, it did not rule out some genetic component to unfortunate life events, he added.
The research suggested that the negative outlook of these families was more likely to be related to the way they interpreted their environment. If you believed your life was being lived under a cloud, then for you it was under a cloud. This propensity could have some as yet unknown genetic component. Another contribution to such a "down-in-the-dumps view" might come from a tendency to "create" bad luck by making bad decisions or by living dangerously, which could lead to misfortune. This, too, might in part be based on a person's genetic make-up.