This was an interesting and enlightening thread. Thank you to everyone who contributed their knowledge to it.
Now, since I have yet to be diagnosed for DID I can not really claim to have it from a doctor's point of view but, this is how things were for me.
On my mother's side of the family there is a lot of mental illness and generally mean-spirited behavior and even violence.
At age three I became self-aware or aware of the fact that I was something that perceived and remembered. Sort of like "I think therefor I am."
Even at that age I had OCD symptoms which I was later diagnosed with in my young adult years.
I don't remember hardly anything after the day I became self-aware save for a memory of a camping trip or maybe even a few trips and then, it was my fourth birthday all of a sudden. There are no other memories between ages three and four for me. I have numerous memories from four to five and most of them are happy memories accept for one that is very disturbing and I believe that it may have been the beginning of me being sexually abused by another family member. I'll not say what it was but, it was disgusting and perverse.
Moving on... Between ages four and five my parents began to argue frequently right in front of me. I saw/heard my mother cry which made me cry in fear and confusion because I didn't know what else to do.
Witnessing these arguments were frightening for me and very hurtful.
Other somewhat disturbing things happened to me before age five that may have only been intended as playful intentions but, it was scary enough to make me run and hide but, it also played a part in my psychological sexual development.
My father left us (our family) twice during these years and it totally destroyed me or what I could have become that fate cheated me out of.
The first time he left was bad enough but, when he returned I dreaded that he would leave me again and he did.
That's when the terrible anger and hate and rage developed and it only happened when someone provoked me to anger and it was like someone flipping a switch and suddenly I was in opposite mode and spiteful and sneaky and in a way even cowardly and for so many years I was lead to believe that this was me just getting angry and having a tantrum but, tantrums don't include sneaking around and finding someone's emotional weak spot and cruelly tormenting it to cause the most maximum amount of pain possible.
It took decades for me to realize that that was my first alternate personality and more traumatic experiences were to follow.
By the time I was in my early twenties that first alternate gave itself a name and invisioned itself a certain way.
More alternates were to follow as I grew older and maybe they'ed been there all along and were forced out by new traumas.
At age 14 I found that when aroused I wanted to be a girl and when the feeling passed I couldn't imagine having such a desire and found the thought of it repulsive.
At age 16 I created a being in my mind to help me through the trauma of being a lonely, bullied outcast.
I had been bullied pretty much throughout my childhood and at age fourteen to fifteen severely bullied by an extremely cruel kid who had it in for me for an entire school year and enjoyed humiliating me every evening on our school bus. The following year I was constantly targeted by other bullies. My life was a living Hell.
I had fantasies of doing things that you hear about on the National News then, felt guilty for the fantasies when the anger subsided.
By the time I reached my late twenties or early thirties I had discovered the internet.

A few years after that I found out about things that surpassed my wildest imaginings.
Years went by as I became more informed and more knowledgeable about certain things and I became aware of another that before I had always thought was just a part of an intense mood. Sometime later I had a run in with another psycho on a forum I had been on for a few years.
We didn't like each other from the start and it all ended badly and caused the emergence of yet another. I'm going to stop here so this doesn't become a damn novelette. So, this is why I believe that I have DID. This and many other experiences. I do switch up for handling different situations or difficult people too. I just want to know what to call this.