Nature vs. nurture in irritability? For example, personally I'm quite irritable. It's not hard to irritate me and I swear either through an inner voice or whisper very often, but not out-loud. That does not happen very often. This is hardly likely due to some temporal cause.

But at the same time it seems there are people who are less irritable. How much of this is due to nature and how much is due to nurture? Are there any studies?
You will have to investigate quite a few factors:


There must be a genetic/epigenetic factors to this because we know that personality trait neuroticism has genetic and environmental factors.
You should also investigate into stress - biological and psychological stress.
Investigating theories of psychological development can also come in handy, especially, Freudian theories.


In my personal view, I think a combination of genetic and environmental factors should play role in shaping irritability tolerance, however, additionally environment plays a role of stressor.

In other words, you should have genetics, epigenetics and upbringing as a predictors of general irritability. Immediate state of being can also have influence, but stressor is like a trigger.