RICHMOND, Va., Oct. 5 (UPI) -- Genes shape people, but so do their experiences and both affect people's levels of anxiety and depression, U.S. researchers found.
Dr. Kenneth Kendler, director of the Virginia Commonwealth University's 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 life.
Studying identical twins allows researchers to study 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, Kendler, the principal investigator, said.
"When I was growing up, in talking about the importance of a good diet, we used to say 'You are what you eat,'" Kendler 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."
The study, published in the journal Psychological Science, found as the twins moved from childhood into late adult life, they increasingly diverged in their predicted levels of symptoms. After that point, however, divergence stopped.
The research team also noted that environmental experiences contribute substantially to stable and predictable inter-individual differences in levels of anxiety and depression by mid-life in adults.
