How do you get Dissociative Identity Disorder?

Ah, now that's a real simple question. Here's the standard equation:
1) you have to be young. When I was diagnosed 30 years age, psychiatrists said you had to be under 3. Now I've read under 5 or even 9 years of age.
And
2) you have to experience an overwhelming or series of, basically horrific events. 99% of DID people suffered some type of abuse, physical, sexual, emotional and/or neglect.
And
3) there has to be little to no adult caregiver attachment. A parent may have been present but unable to properly live, care and protect the child, an alcoholic, emotionally unstable, never home, etc.
Those are the three main factors that contribute to the development of DID.
Personally, I'm also leaning towards thinking that there may very well be a genetic predisposition to DID.
How did I end up Multiple (My favorite term for people living with DID, from the old and more easily understood diagnosis of Multiple Personality Disorder)?
A) my mother was incapable of love, tried to drown me in the sink when I was way little, allowed my father to physical assault me, knew and allowed the incest, dad's sexually molesting me on a daily or weekly basis.
B) my dad and the chronic sexual abuse. Torture at his hands, both for his pleasure and to keep me quiet.
C) being neglected, not getting enough to eat, starving for days, going without appropriate clothing, having the household heat turned off, living with maggots and garbage in the basement.
It's a recipe for an extreme case of DID. Being autistic, I do believe I was genetically predisposed to creating alternate personalities, "alters" or as I call them "people". The alters are psych parts of me that split off during the traumatic incidents. When I couldn't handle the pain/torture anymore, I'd create an alternative personality to absorb the hurt and the memory. Because my assaults were daily or weekly, I'm a rather complex Multiple.
I've been in therapy since I was 23 and I'm 54 now. There was about a 9 year span when I didn't have insurance so no therapy, otherwise I've been working to remain functional, productive and not nuts.
So, DID happens to children who are traumatized.
More later