It is not allowed to share personal information. I would imagine twitter and facebook count as that.

 

In your profile, under Contact Settings you can add all that information. People can access it by checking your Profile page and clicking on the "Information" tab. Not sure if it is wise, but there is a place in your profile to add the info.

 

Just remember that if you put something out there on the internet it'll be there forever. If you're okay with having your real name linked to your ign then it's probably fine.