There is a natural ability inherent in hypnosis, but willingness goes a long way toward overriding that.
I would rather work with a willing participant who is low on the hypnotizability scale than someone with a ton of natural ability who won't do the work.
There are people who are naturally gifted at hypnosis. They are known as "somnambulists" or "sleepwalkers". While somnambulists have a natural ability to experience hypnotic trance, it is a skill that can be learned and improved by anyone who is so inclined. Practice, practice, practice.