Shortly before my father died, he told me that I was to continue with my flying and do my darndest to fly professionally. Unfortunately, he was too ill for me take him for another flight.
And my mother keeps nagging me to get on with my training so I can take her flying again.
The point of this, is that my parents both came/come from an aeronautical background and therefore have some understanding of what's going on up there in the sky (and the rotorhead!!).
Garfs, I suspect that your parents reluctance is just lack of information and knowledge. If you take them for a trip, explain how it works and what happens when various emergencies arise, their fears may be allayed.
The statistics quoted are so small that to apply a % difference between fixed and helicopter is a nonsense; one more fixed wing accident per 100,000 and the stats are on par!!
Cheers
Whirls