Nothing enrages astronomers more than when people mistake them for astrologists. The idea that your fate is sealed by how the stars were aligned on your birthday is most definitely not science. But a new study offers evidence that your future actually can be influenced by the time of year you were born.
Children born during the dry months of the year in Gambia bear modifications to their DNA that may have all sorts of implications for their lifelong health, scientists report April 29 in Nature Communications. But far from demonstrating that the stars control our destiny, the research shows that the environment a mother experiences, and especially what she eats, around the time of conception can have a profound effect on the behavior of her child’s genes throughout life. Being conceived by a starving mother, for example, may ramp up genetic processes that stretch out calories in hard times.
Babies conceived in Gambia during the rainy season, when nutrient-dense veggies are available, had differences in certain tags that affect how genes behave compared with babies conceived during the dry season, when calories abound but nutrients are scarcer.
The different seasons influenced six parts of the babies’ genomes. These changes weren’t to the primary DNA code—the C’s, G’s, T’s and A’s that make up our genetic playbook. Instead they attached important decorations on the DNA molecules that regulate how the DNA works. These attachments, called epigenetic marks, leave the sequence itself untouched but modify its activity, sometimes by dialing it down.
Scientists don’t yet know whether the particular changes found in the Gambian babies have important consequences. But results from other studies, many of which are described by my colleague Tina Hesman Saey in her March 2013 feature From Great Grandma to You, suggest that these decorations aren’t just for looks.
The horrific Dutch famine during the winter of 1944 to 1945, for instance, offered a way to study how nutrition affects the epigenome. People born to mothers who were pregnant during that Hunger Winter had altered tags on a gene called IGF2 that regulates human growth and metabolism, scientists have found, an effect that has persisted for more than 60 years.
Other research focuses on the opposite, a situation that’s more common in the United States: people born to obese parents. Obese mothers are more likely to have obese children, and some scientists think that part of the reason for that is epigenetic changes. Dads aren’t off the hook, either. Obese men have daughters have too little of a certain tag on the IGF2 gene, scientists reported last year.
So far, most of the other studies on epigenetics have focused on potentially harmful things. Stress, smoking, alcohol and pollutants have all been shown to influence the behavior of genes.
But the news isn’t all dismal. A notable exception comes from research on exercise. Working out during pregnancy, for instance, seems to change the behavior of some genes in a good way, studies on mice have found.
Many of these studies don’t follow the effects through many generations, so it’s not clear whether the alterations actually do persist for eons. But the suggestion is that certain aspects of the environment, like whether there’s enough food around, can influence our genetic history.
This is all to say that the behavior of your genes is not written in the stars. Nor is the behavior of your children’s or their children’s. Genes are susceptible to very real influences here on Earth that, unlike astrology, can prepare us to meet our fate.