Board Thread:Wiki Discussions/@comment-24772621-20140501232434/@comment-24874466-20140506010859

Several did know. All the Kage knew Naruto's lineage and Yamato and Kakashi knew as well. Shukaku probably put two and two together and figured it out. Inoichi could have done the same, and by knowing Inoichi and Shukaku, Choza could have found out. I think those people did know, but weren't allowed to tell Naruto.