I have been involved in air experience flights both in rotary and fixed wing for over 25 years with youngsters from the age of 6 up to 16 in a wide range of aircraft from a Cessna 150 to the S61N.
I have taken each of my own 3 boys flying from when they have all been under 1 year old. The risk is not in the flying but in the mind set.
They are now 12, 5 and 3.
They love it and regularly fly with me. However my wife, with 20+ years as cabin crew, cannot get her head around the whole pilot thing (yet she still wants the occasional jolly with the boys) and wonders why I want to "stall" the helicopter when coming into the hover!!!
The boys just roll around laughing at her
The basic premise in my opinion is: D'ont be nervous, explain what you are doing, and be aware of your own and their limitations and make the experience an enjoyable one. And as has been pointed out, young children tend to go to sleep anyway so it is the parents you need to worry about
Safe flying
AMCP