Both genetic and environmental factors affect people’s risk of developing post-traumatic stress, according to new research that illustrates how nature and nurture combine to shape health and behaviour. A particular genetic variant makes people much more susceptible to post-traumatic stress disorder (PTSD) after harrowing experiences, but only if they have also had an abusive childhood, scientists in the United States have discovered. The findings add to a growing consensus that the debate about whether mental health, personality and behaviour are driven by nature or nurture is founded on a misconception. They indicate strongly that genes and the environment are not mutually exculsive forces, but rather work together to influence human development. PTSD is a serious anxiety disorder that develops among people who witness or experience unpleasant events, such as war, murders, terrorist attacks or natural disasters. It commonly leads to nightmares, insomnia, flashbacks, mood swings and depression, and can severly impair people’s ability to live a normal life. Not everybody who experiences severe trauma develops PTSD, and the risk is known to be influenced by genetics. Studies of twins who served in Vietnam showed that identical pairs, who share all their genes, are more likely […]