Umm, well, assuming I actually have it. I'm not entirely sure... if I had to guess I'd say childhood abuse (physical and emotional), what typically manifested as abject hatred from my father, alcoholism, and domestic violence.
But I'm not sure if that's the real answer. I was also hit by a car on the autobahn as a small child. Yeah, I ran out into traffic. Good one. Thrown several lanes, unconscious, I remember it very clearly and can see everything happening including my mother and the guy who hit me standing there crying and thinking that I was dead. It's possible that's it. It does seem weird that I can visualize and almost feel the entire incident still. But it doesn't really scare me. Just makes me a little wacko about traffic safety.
I also witnessed a rape as a kid, tried to stop it and could not, I was held away, tried to get help to stop it, nobody listened, tried to tell and nobody even believed me. That had the worst effect and seems the most likely answer to me, personally. Around the same time I was also sexually assaulted by another kid and, while I am really resistant to acknowledging it, I was most likely molested by a house guest.
Was raped in college. Spent the next year and a half in a daze. Several years later, had an abortion that was extremely traumatic for me. It led to a pretty major breakdown and an eating disorder. Hyperemesis gravidarum (that's "morning sickness" that lasts day and night through an entire pregnancy.) The previously mentioned eating disorder was bulimia, so some good came of this- I think that may have been thoroughly eradicated on account of this particular experience... followed by a traumatic birth, which brought on another breakdown and brought me here.
(edited for clarity)
There have been other possibilities, I guess. Bullying and isolation throughout childhood. Multiple car accidents (involving drunk drivers...). Really shitty jobs that bordered on traumatic. Sexual harassment on multiple occasions including sexual assault by an employer while locked in an office alone. I don't see any of these being the answer, though.
So, who knows which response is accurate for the poll. *shrug* I picked childhood abuse, etc.