Early trauma linked to developing wartime PTSD:

Note: I have not had a chance to see the original article myself and
evaluate the interpretation of this author. Also, those of us working with
traumatized people have long assumed that early trauma predicts development
of PTSD with later traumatic events. For reasons of principle, I also
would not want it to be said (without strong support) that family violence
is the problem, and the violence of war does not hurt soldiers.

*Embattled Childhood: The Real Trauma in PTSD*

From the article

All the Danish soldiers who developed PTSD were much more likely (compared
to resilient soldiers) to have suffered emotional problems and traumatic
events prior to deployment. In fact, it wasn’t traumatic war experiences
that predicted the onset of PTSD, but rather childhood experiences of
violence, especially punishment severe enough to cause bruises, cuts,
burns, and broken bones. PTSD sufferers were also more likely to have
witnessed family violence, and to have experienced physical attacks,
stalking or death threats by a spouse. They were also more likely to have
past experiences that they could not, or would not, talk about.