It could be a combination of things like temperment, frustration and training.
I have what has been called an Irish temper, dating back to when I was a kid. I was told early on that losing my temper could get me into BIG trouble, as in 'thrown in jail' type trouble. I've kept it under fairly good control over the decades. (It is one of the reasons I do NOT do alcohol or drugs.)
The times that I've lost it are usually when I'm trying to do something that needs to be done and I've run into 'major' problems. If I don't quit and step back to calm down, I go ballistic and start yelling and breaking things. I do have enough control to NOT break things that are irreplaceable or of sentimental value. I also avoid physical and verbal abuse of people. But it isn't pretty. The family walks on egg shells when I reach that state.
Thankfully it is very rare and, with one exception, never in a work or public environment.
When I look at the reasons I get angry, the 'major' problems are usually relatively trivial in the overall scheme of things. I'm not sure you could call them random aggression though.
I have seen households where anger and fighting tend to be the status quo, so that could be a contributing factor in some instances. Your 'training' as you grow up can manifest itself in later behavior.
