Why your DNA isn’t your destiny

The new science of epigenetics reveals how the choices you make can change your genes ─ and those of your kids

By John Cloud

Time Magazine, 18 January 2010

  • … research showing that conditions in the womb could affect your health not only when you were a fetus but well into adulthood.
  • In 1986, for example, the Lancet published the first two groundbreaking papers showing that if a pregnant woman ate poorly, her child would be at significantly higher than average risk for cardiovascular disease as an adult.
  • Charles Darwin, whose On the Origin of the Species celebrated its 150th anniversary in November, taught us that evolutionary changes take place over many generations and through millions of years of natural selection. But Bygren and other scientists have now amassed historical evidence suggesting that powerful environmental conditions (near death from starvation, for instance) can somehow leave an imprint on the genetic material in eggs and sperm. These genetic imprints can short-circuit evolution and pass along new traits in a single generation.
  • … the data suggested that a single winter of overeating as a youngster could initiate a biological chain of events that would lead one’s grandchildren to die decades earlier than their peers did.
  • At its most basic, epigenetics is the study of changes in gene activity that do not involve alterations to the genetic code but still get passed down to at least one successive generation.
  • It is through epigenetic marks that environmental factors like diet, stress and prenatal nutrition can make an imprint on genes that is passed from one generation to the next.
  • We all know that you can truncate your own life if you smoke or overeat, but it’s becoming clear that those same bad behaviors can also predispose your kids – before they are even conceived – to disease and early death.
  • … scientists are learning to manipulate epigenetic marks in the lab, which means they are developing drugs that treat illness simply by silencing bad genes and jump-starting good ones.
  • The great hope for ongoing epigenetic research is that with the flick of a biochemical switch, we could tell genes that play a role in many diseases – including cancer, schizophrenia, autism, Alzheimer’s diabetes, and any others – to lie dormant.
  • When a methyl group attaches to a specific spot on a gene – a process called DNA methylation – it can change the gene’s expression, turning it off or on, dampening it or making it louder.
  • Other recent studies have also shown the power of environment over gene expression.
  • … epigenetics isn’t evolution. It doesn’t change DNA. Epigenetic changes represent a biological response to an environmental stressor. That response can be inherited through many generations via epigenetic marks, but if you remove the environmental pressure, the epigenetic marks will eventually fade, and the DNA code will – over time – begin to revert to its original programming.
  • … memory – a windly complex biological and psychological process – can be improved from one generation to the next via epigenetics.
  • Jean Baptiste Lamarck (1744-1829) argued that evolution could occur within a generation or two. He posited that animals acquired certain traits during their lifetimes because of their environment and choices.
  • … there is a general mechanism for transmitting information about the ancestral environment down the male line… In other words, you can change your epigenetics even when you make a dumb decision at 10 years old. If you start smoking then, you may have made not only a medical mistake but a catastrophic genetic mistake.
  • Scientists had mapped only a certain portion of the epigenomes of two cell types… There are at least 210 cell types in the human body – and possibly far more… Each of the 210 cell types is likely to have a different epigenome… The human epigenome contains an as yet unknowable number of patterns of epigenetic marks… certainly in the millions.
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