You are what you have experienced

In addition to our genes, our life experiences are important influences on our levels of anxiety and depression, according to a new study. Principal investigator Kenneth Kendler, M.D., director of the VCU Virginia Institute for Psychiatric and Behavioral Genetics, and an international team of researchers from VCU and other universities, analyzed nine data sets of more than 12,000 identical twins with symptoms of depression and/or anxiety through the lifespan. Studying identical twins allowed researchers to have a pair of individuals who are born with identical genetic compositions and a shared family environment. Their environments may begin to change as they begin to make divergent decisions as they get older that come with lifestyle, diet or friends. The study found that as the twins moved from childhood into late adult life, they increasingly diverged in their predicted levels of symptoms, but after that point, stopped further diverging. Further, they noted that environmental experiences contribute substantially to stable and predictable inter-individual differences in levels of anxiety and depression by mid-life in adults. "In this time of emphasis on genes for this and that trait, it is important to remember that our environmental experiences also make important contributions to who we are as people," said Kendler. "When I was growing up, in talking about the importance of a good diet, we used to say 'You are what you eat'," he said in a statement. "What this study shows is that to a substantial degree, 'you are what you have experienced.' That is, your life history stays with you in impacting on your background book, for good or for ill," he added. The study has been published in Psychological Science.