User blog:Alex1496/How did we get the characters' birthdates?

I've seen that most of the characters' infoboxes include their birthdates, but apart from Butters' and Kyle's, i have no idea where they are taken from. Please leave a comment with the source of every character's birthdate, as i would really like to know (editing the respective page would help too). Help is appreciated. Thanks.Signatures/Alex1496 19:29, May 13, 2010 (UTC)