Post traumatic stress is a normal response by the brain to extreme or prolonged experiences where survival is in question. Traumatic experiences early in life set the stage for many 'disorders' and research is showing a connection to childhood trauma and adult PTSD, depression, anxiety, and substance abuse.
trauma is not rare...
"Going through trauma is not rare. About 6 of every 10 men (or 60%) and 5 of every 10 women (or 50%) experience at least one trauma in their lives. Women are more likely to experience sexual assault and child sexual abuse. Men are more likely to experience accidents, physical assault, combat, disaster, or to witness death or injury."
-Jessica Hamblen, PhD and Erin Barnett, PhD
"If you're an adult and life's been good to you, and then something bad happens, that sort of injures a little piece of the whole structure. But toxic stress in childhood from abandonment or chronic violence has pervasive effects on the capacity to pay attention, to learn, to see where other people are coming from, and it really creates havoc with the whole social environment; it leads to criminality, and drug addiction, and chronic illness, and people going to prison, and repetition of the trauma on the next generation."