Is it illegal or legal to befriend a child on a video game?

I can't really control the fact that child tend to befriend me online. I am an adult gamer and I can not seem to control the amount of children who wish to speak with me. I try and tell them that I am an adult and I'd rather not be friends with them but they don't seem to care and I really don't know what to do. I'd rather speak with people I know in real life. I don't mind having adult friends online or people who are mature but like I said... I cannot control these children. They pour out their personal stories to me and its quite crazy. I've heard many disturbing stories from people claiming to be children. I mean how can anyone know for sure what these people say is true? I just want to know if its illegal or legal to befriend a child on a video game in the state of Ohio. Children seem to be attached to adult figures nowadays. What is the proper way to do this? I could care less about meeting a child. However, I don't believe in being mean or rude to a child if they talk to me.