‘Babies born into poverty are damaged forever before birth’, ‘Mother’s diet during pregnancy alters baby’s DNA’, ‘Pregnant 9/11 survivors transmitted trauma to their children’. These recent headlines may sound like fanciful pseudoscience, but all of them have their basis in a legitimate and increasingly prominent field of scientific study – epigenetics. Epigenetics deals with the fact that although our genes are replicated throughout most of the cells of our body, different genes are expressed in different parts of the body and at different times. Chemical changes can alter the effect of our DNA, without there needing to be any change to the sequence of the DNA itself. Such changes can occur in response to our circumstances, can endure within our lifetimes, and can even be inherited by our children and grandchildren. A simplistic way of summing this up (which fails to do justice to the subtleties involved) would be to say that contrary to what you were told at school, Lamarck was right – we can inherit acquired characteristics.

For campaigners who have long argued that early infant experience determines wellbeing in later life, and that we should therefore take great care in raising our children, this seems to be a vindication from science. It also suggests that even if we don’t care about our own health, we should realise our bad habits may be harming the next generation. Epigenetic studies have linked unhealthy diets and the effects of pollution to asthma, diabetes and obesity in our offspring. One recent article on the subject was titled: ‘We are what our mums ate.’

Nevertheless, critics – and even some of the key figures within epigenetics – take issue with these conclusions. Does epigenetics really provide scientific justification for what some see as a moralistic outlook on how we affect our children? Why has the field become so prominent now, a full 70 years after the term ‘epigenetics’ was first coined by the biologist CH Waddington? And does epigenetics finally break down the distinction between the natural and social sciences, or is it all the more important to disentangle the two?

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