Should QA/testers write unit-tests?

I work as a test engineer. I mostly work with test-automation on a functional-system level, and performance testing.

I got asked by the scrum-master to start doing some unit-tests, but I have some questions in my mind before I answer that question.

1. Should testers do unit-tests at all? Isn't that the developers job? Why must I do that?


2. How hard is unit-testing? Is it easy stuff or complex stuff? I choose this career because I was never a good programmer. But my programming was good enough to start working with test-automation (very easy stuff).