What if the military were able to identify people that were more or less susceptible to PTSD?
Research in America has found that DNA may determine how vulnerable or resilient people are to post-traumatic stress syndrome.
It's part of a massive £29 million ($43m) study involving researchers and scientists from across the US.
Differences in resilience may be due to genetics, as Hannah King reports.
If you think you or a loved one might be suffering from symptoms of PTSD, contact either of the charities below.