Hello apleee: You know... anger, & the control of it, is something I have struggled with as well.

Honestly, I don't know why you're the way you are. If it is even possible to determine this, it would take a mental health professional, a psychologist or psychiatrist, to ferret it out I would presume.
I know, in my own case, there are both physiological as well as experiential things in my past that I could point to that could have been contributing factors. I know that there are certain varieties of brain damage that can cause one to lose the ability to control one's anger.

And there are some things in my past that might have contributed to something of this sort. But I also was verbally & physically bullied throughout junior & senior high school years by a gang of older boys. Everyone knew what was going on. But no one did anything. So that could certainly be a contributing factor as well. And there was other stuff.
Regardless, there's nothing I can do about any of that now.

So I simply strive to be mindful of what's going on with me so that when I begin to feel my anger swelling, I have the opportunity to choose a different path.