Family Violence: Trauma from family violence can predispose an individual to PTSD. It has been shown that the disturbing memories are greater contributors to the biological and psychological dimensions of PTSD than the event itself.
Genetics: There is evidence that vulnerability to PTSD is hereditary. Approximately 30% of the variance in PTSD is caused from genetics alone.
Military Experience: This one can go further than the military to law enforcement and other fields where one faces trauma daily. Studies have shown that those prepared for the potential of a traumatic experience are more prepared to deal with the stress of a traumatic experience and therefore less likely to develop PTSD.

Do you need someone to talk to about PTSD? Family Psychiatry and Therapy is always here to listen.