From The Guardian:
The Olympic Isle on opening night was “full of noises, / Sounds, and sweet airs that give delight and hurt not”. The lion of the industrial revolution could lie down with the lamb. But beneath the fantasy a sewer ran, diverted but untamed: the spectre of doping. And not just doping, because this is the age of genomics: gene doping. The man who came to warn of this prospect is himself a Spector: Tim Spector, professor of genetic epidemiology at King's College London and the author of this book. The means by which gene doping might be achieved (no one is sure whether it has yet been, or in practice can be, done) is Spector's field of expertise: epigenetics. So he has become a media pundit during the Olympics, but his real subject is twins and what they tell us about genes. Identical twins are a unique test of genes in action because, having come from a single fertilised egg, they have identical genomes, all 3bn letters of them. They are clones. The point about twins and identical genes is that genes in action do some strange things that we are only just beginning to understand – identical genes can diverge in their expression during the course of a lifetime. This is epigenetics. It is now generally accepted that personal experience can change our genes. If you practise music for six hours a day and become a great musician, your brain will show recognisable changes both in large-scale anatomy and genetically. London cabbies have “knowledge” – enhanced regions of the brain that start to recede when they retire. The chemical processes that alter the genes in epigenesis – methylation and deacetylation of the packaging proteins of the genes, the histones – are fairly well understood. But the puzzle is that some of these changes can be passed on to offspring, and the effect – although it eventually disappears after three to four generations – can have profound consequences. One hundred and fifty years of biological orthodoxy claimed that these phenomena were impossible. What is supposed to happen at reproduction – and mostly does – is that all the epigenetic marks acquired during life are erased and every birth is a fresh start. But the case of Dolly the sheep and other animals cloned since then show that where adult cells have been reprogrammed to wipe out the epigenetic marks, the process is inefficient. So Dolly, whose parent cell was six years old, was not really a fresh start. She died prematurely as a result. But even in normal reproduction, it seems that some epigenetic marks can persist for a few generations.
Spector explains these facts clearly and does not overdo the deep biology. Most of the book consists of case histories and studies of the crucial traits that matter to all of us: intelligence, athletic and artistic skill, disease, obesity, sexual orientation. What the genomic revolution has done is to reopen the old nature/nurture debate. How wildly this has lurched, protagonists on both sides blithely ignoring what little evidence there was. Spector recalls that in the 1960s and 70s it was almost possible to obtain funding for research on twins because of the prevailing blank slate, nurture-is-all ideology. This was preceded by the appalling eugenics period when, despite the evidence that hereditary genius dissipated over the generations, far too many serious biologists endorsed the idea of breeding the best and brightest and preventing this in the unfit. Today there are fewer excuses because the solid evidence is piling up. But the evidence is often puzzling. To the embarrassment of the Human Genome Project, researchers have come to the conclusion that the genetic component of some multi-factorial diseases is exceptionally low. Many genes have been found to be implicated in such conditions but their overall contribution might be as low as 2%.
More here.
