I have several QA engineers working with me. Their job descriptions include performing exploratory tests, analyzing the output of automated nightly test runs, creating tools and utilities to generate data and analyze logs, etc.
That leaves a vast array of things that are not our job.
My first question is, "who cares?". We work in a small company. We're here because we want to do exciting and interesting things. We're not here to make fiefdoms. And that means that job definitions are a bit incomplete. If it needs to be done, and you know how to do it, then it's your job. Congratulations!
I don't have a lot of patience with people who declare that something is not their job. If you have the time to make that statement, then you have the time to say something more helpful, like, "I'll do it" or "I don't know how to do that. Hey, Fred, can you help?".
So quit telling people what isn't your job, and start saying and doing something useful.