Are fat people fat because they’re greedy – gluttony being one of the Seven Deadly Sins – or are they fat because of their genes? And are slender people in shape because they were lucky enough to be born that way? Science, it seems, is increasingly coming down on the side of genes. A new study from the University of Cambridge tells us that “the key to staying slim is skinny genes. Slim people have a genetic advantage when it comes to maintaining weight.” We have all known individuals who could stuff their faces with chocolate eclairs all day long and still retain their beanpole shape, while others among us struggle daily with the conflict between gluttony and self-control (or, alternatively, greed and vanity). So it’s plausible when Professor Sadaf Farooqi says that “this research shows for the first time that healthy thin people are generally thin because they have a lower burden of genes that increase a person’s chances of being overweight.” She also warns the slim against imagining themselves morally superior to fatties. Their shape is not a virtue, but an inheritance. Yet taken too literally, this report could be seen as another nail in the coffin of free will and self-control – “self-mastery” being a virtue extolled by the ancients. If our persons are dictated by the lottery of our genes, then we have no responsibility for our decisions. Free will is replaced by passive fatalism. Fortunately, there are physicians and researchers who see a middle way. Since the obesity level of the general population has increased in nearly all developed societies in recent decades – 62 per cent of people in England are now clinically overweight – it follows that more people have been eating more, exercising less, and sitting around on the sofa scoffing cream buns. I well recall visiting communist Albania in the 1980s, where private cars were banned (except for party officials). Everyone walked everywhere and manual labour was the norm. And everyone was slim – except for party officials. We have, surely, genetic dispositions towards the shape we inhabit. But that’s not the whole story, and free will and the choices, good or bad, that we make are relevant. Gluttony clearly remains culpable.