I have red hair
Nice, it occurs naturally in 1–2% of the human population so you are quite lucky!
I knew it was rare, but not that rare. I also have green eyes, and I know that is rare too.
That is quite a rare combination. It happens due to an altered version of the MC1R protein in your genetic makeup
So it is kind of like a mutation?
Not per se, it just means your body produces high levels of the reddish pigment pheomelanin.