The books that are being published don’t have a rating system. We need safe and easy eating on books so we can can choose the appropriate book(s) for our children or ourselves based on age, violence, sexuality, and nudity. 
Unfortunately books aren’t rated like movies and video games. With social media promoting books (which is great seeing the younger generation interested in reading more) it is unbelievably easily for young children to pick a book that can contain inappropriate content for their age.