Why Are Some People More Angry Than Others?

I have always been referred to as a short tempered person. The biggest problem is I know that very well but can also provide justification for my actions, at least in most of the cases :D

Most so called studies claim that people like me have low tolerance level for frustration.
Now, why does that happen? It might be genetic/physiological; some children are born irritable, touchy, and easily angered. It seems that family background does also play a role; a chaotic home environment does not nurture true growth of any emotion. Being exposed to people who resort to anger to win over others, gives a child a wrong idea.
Providing a superfluous lifestyle where every demand of the child is met with, hardly gives a sense of adaptability and resorting to what is available. A minute discourse in the normal turn of events thus infuriates such a person.
Society claims anger is one word short of danger, but never teaches one to handle this perfectly normal human emotion constructively.

Now, what if I tell you that none of the above arguments would work for me. I was not born irritable. I was not raised in a disruptive family. My working mother even with her mother-in-law being a total jerk, never let me feel the pain or suffering she had to go through balancing work and family. I was mostly taken care of by my aunt, before she got married and left for her new home. My father never let me understand that with even my mother working, there was a time when they had to worry about how to take care of the next month finances. Its true I lived my life superfluously; a Rs. 15 Dairy Milk every month from my grandfather, travelling to nice places using my parents' bank LTC/LFC and dinner at a fancy restaurant on my parents anniversary were the things which I looked forward to the most. So, I had an enjoyable and comfortable childhood in my middle class family.
When it comes to adaptability, being a single child however didn't hinder me in anyway. I had a lot of cousins and thanks to them, being selfish was not an option :)

So, what went wrong? Actually, I gained this title soon after I stepped out of my teens. Of course, my teenage years had its natural toll of differences between mother and daughter on what to and not to do/wear/behave/say/expect and so on. This occasional nonsense was totally normal. But now, I considered myself to be a grown up, and just wanted people to treat me that way. A famous incident when my anger almost stopped a college performance by two of my very good friends. I still get to hear how hot headed I behaved. But no one asked me why I behaved that way, instead they just assumed that is how I am, irrational and impulsive. They never got the idea that circumstances can build up and a small push to a frail guy away from your body can cause him to lose balance. Don't worry, I didn't push him off the roof ;)
Later on, with more studies and pressure, I didn't have time to get angry. It was not that there were lack of incidents to irritate me, but I simply kept my cool.
The disadvantage of being a girl in a science environment is that to be social you have to hear continuous stream of sexual innuendos even if you don't want to. The good thing was, my adaptivity and high tolerance level made me immune to all these rants and helped me to enjoy the humour instead of taking offense. Now, this high tolerance that I boast of, is of course highly relative !
To whom one can be tolerant to? I am tolerant to people whom I respect, whom I can trust to a certain level even with all their shortcomings. However, there is a separate class of people to whom I show tolerance of a different kind, they are people whose opinion does not really matter to me. So I don't waste my energy arguing to convince stubborn people to open their minds.
However, why do I loose my cool with my friends, the person I used to love and my parents? Is it because that I expected them to understand me, expected them to believe in me and to trust me more than they can trust others? My parents are the more sensible of the lot, they understand my stress in my career and how I cannot settle down in life. My so called friends, always criticized me about having a fit of rage, a person who blows things out of proportion. But what they never saw were the circumstances which could have led to what they call a drastic outburst of emotion. I have been advised by a well read person that I should go for psychiatrist treatment. But why on earth, should I pay someone to tell me what any normal person without a degree in psychology can? Is it really so hard to find a person who instead of instigating the anger when someone is already irritated can actually calm the latter?
Anyways, too much of rambling after almost 2 years. Keeping a control on the anger issue, not very hard with the absence of such instigating people around me :)