Is it normal to have sex dreams?

I'm a 18 old girl and I've never had sex and never watched porn, nevertheless I often have this kind of dreams (well-detailed dreams too!): my subconscious doesn't censor anything! I don't understand where all that material comes from. Do I have an over-developed imagination? Or maybe in my past life I was a hooker or a womanizer and my dreams are the "remainder" of those past memories?