Holocaust survivors pass on trauma through their genes, making their children and possibly even grandchildren more susceptible to PTSD and other stress disorders, according to new research. The Guardian reports researchers looked at 32 Jewish men and women who survived traumatic experiences at the hands of Nazis during World War II and their children. They found that parents passed their life experiences onto their offspring by altering their genetics in a process called "epigenetic inheritance." In addition to affecting how well children of trauma survivors cope with stress, these genetic changes could also put them at increased risk of obesity and hypertension, according to Scientific American.
“The gene changes in the children could only be attributed to Holocaust exposure in the parents,” says researcher Rachel Yehuda of Mount Sinai Hospital in New York. The Guardian explains that people's genes are modified by their environment through chemical tags that attach themselves to DNA, and researchers found these tags on the same part of the stress-hormone gene in both Holocaust survivors and their children. According to Scientific American, the children had less cortisol—a hormone that helps recovery from trauma—and higher levels of an enzyme that destroys cortisol. Researchers aren't clear exactly how gene changes are inherited as chemical tags were previously assumed to be cleared before DNA is passed on to offspring during fertilization. (An old letter led to a grim Holocaust discovery.)