Maybe we should define "kid", but there is definitely an age under which parents should censor which books they read, which movies they watch, and which games they played.
No doubt. I don't think I'd want any kid playing any violent video game until they get to the age where they understand that nobody is really dying; where it would bother them so much that they would have nightmares.
When I was 7, I went with my 4-year-old brother to the Saturday matinee on the base. It was a sci-fi movie where aliens were invading the earth. He started crying as though he thought they were actually invading. I didn't want to leave, but I knew that he wasn't ready for it yet so we left. I called my mom from the lobby to pick us up.
When I was 4, I started reading adult books to increase my vocabulary. At first, I had to look up nearly every word but that was the point. By the time I was 8, I picked almost all the books I read from the adult section of the public library. I used to bring them to school so I wouldn't get bored when we went as a class to the primary school library. The teachers never complained about it, and fortunately for me my mom was very tolerant about what I could or could not read.
I remember the first time I read an 'expose' about government corruption. My dad wasn't very thrilled about it. He wanted to make sure I understand that it was one man's opinions. That not everybody believed that way. Well, duh.
When I was 9, I started sneaking into my parents' bedroom to read Playboys, the Marquis de Sade, The Story of O, The Tropic of Cancer, Mandingo (apparently my mom had rape fantasies about black slaves...), you name it. They had quite an extensive collection of classic porn.
When I was 15, my parents first mentioned sex to me. Ha. Little did they know...