Research has indicated that trauma is not just psychological, but biological and even heritable.
New evidence has suggested that traumatic events - such as the September 11 attacks or London's July 7 bombings - really can affect the genes, and lives, of children as yet unborn.
By altering the chemical mechanisms regulating gene expression, these modifications may become embedded in the male line, and can be passed on to the victim's children, reports the Age.
This is a controversial concept, because it seems to cast doubt on one of the key principles of modern evolutionary theory. According to the scientific orthodoxy, our only genetic inheritance from our parents is our DNA.
Yet this, it now appears, is not entirely the case. Embedded within the DNA sequence are epigenetic regulators, chemical marks that control which genes are expressed and which are not. The heretical proposition is that these epigenetic marks can be transmitted along with the DNA - and the latest findings, indicate that psychological conditions, such as trauma and stress, also leave an epigenetic mark.
The question remains: can these effects be inherited? Research is suggesting that the answer is yes. In the case of Holocaust survivors a high proportion show abnormally low levels of the hormone cortisol, a deficit of which is associated with PTSD.
What is surprising, though, is that their offspring have equally abnormal levels - and this has been shown to be a biological trait, rather than an effect of the parent-child relationship.
The good news is that adverse epigenetic effects are reversible.