Because parents are very over protective over their children reading these type of books. Also some kids got nightmares. I believe that kids could read these on the age of 7. Their is no blood scenes. To prove this I have read all the goosebumps books. Parents should control these things because they are just suggesting their opinion and make it happen without discussing with other parents around the country. Kids get nightmares from not from scary but weird things or Disney!
