A study of Holocaust survivors and their children has shown that trauma can be passed on through genes.

The study, led by Rachel Yehuda from New York’s Mount Sinai Hospital, looked at the genes of 32 men and women who directly experienced the Holocaust - either in a concentration camp or who had to hide during the Second World War.

According to the research, the survivors’ children had an increased likelihood of stress-related disorders, as well as low levels of cortisol, the hormone that regulates the body’s response to stress. Ms Yehuda said: “The gene changes in the children could only be attributed to Holocaust exposure in the parents”.

The idea that environmental factors such as smoking or diet can affect one’s offspring via genetic mutations is known as “epigenetic inheritance”.
Ms Yehuda’s team were specifically interested in one part of a gene associated with the regulation of stress hormones.

“It makes sense to look at this gene,” said Yehuda. “If there’s a transmitted effect of trauma, it would be in a stress-related gene that shapes the way we cope with our environment.”

The epigenetic tags representing trauma found on the Holocaust survivors’ genes matched the tags found on their children’s genes.

The idea is a controversial one and it is still not fully understood how these tags are passed on. It was believed that any epigenetic tags on DNA are ‘wiped clean’ following fertilisation. However, recent research form Cambridge University has shown that some epigenetic tags escape this cleaning process.

“To our knowledge, this provides the first demonstration of transmission of pre-conception stress effects resulting in epigenetic changes in both the exposed parents and their offspring in humans,” said Ms Yehuda, whose work was published in Biological Psychiatry.

Marcus Pembrey, emeritus professor of paediatric genetics at University College London, said: “What we’re getting here is the very beginnings of a understanding of how one generation responds to the experiences of the previous generation. It’s fine-tuning the way your genes respond to the world.”