BTW, I was re-reading the manga and happened upon the same line and thought it was interesting,
(What Orochimaru is thinking in the middle pane)
I think we will find out more about Naruto's History when either the series/manga/etc story gets to 3/4ths the way finished, or at the end...about 5 anime episodes before the end of it. It will most definately happen before the end...
I think both Jiraiya and Kakashi know more about it, as well as other Konoha Jounins...I also believe the Akatsuki know a great deal about the Kyubi, as well as other demons...and who the hosts are if there is one...
Also, they could be keeping the history a secret from Naruto because there is a chance this could awaken Kyubi, etc, or at least cause issues for the Seal in some way...they dont know how Naruto might react to the news...something else to ponder on...
This is something else I think that has gone down:
Orochimaru became a part of Akatsuki, He allowed the group to know who was the host for the Kyubi, he had a fight with Itachi/or he realized how much potential Itachi had, and decided he wanted that as well, so he left the group to find Sasuke...he could have also left the group because he knows what Akatsuki wants to do with Naruto...
Also, The reason for the Third Hokage to create the rule about not telling anyone about Kyubi being inside Naruto was to protect him from those like the Akatsuki, as well as to allow him a chance to integrate with society. This is why I believe only the top tier of Shinobi from Konoha know of this...however, since both Jiraiya and Kakashi were linked with Yondiame, its likely they know more information...same as Sarutobi, but he is kinda dead now,
Some Speculation on my part:
First Hokage=>???=>Tsunade/Nawaki=>???
Second Hokage=>???=>Jiraiya=>Yondiame=>Naruto ...
???=>Sarutobi=>???=>Konohamaru...
Also, not quite sure where Sarutobi and Konohamaru fit in, but they also could be part of this family...it would only make sense, unless none of them end up related after the history is revealed.
We haven't been told who Konohamaru's Parents are either...there has to be a reason for it,
Also, I believe the one who will either kill or die with Orochimaru is Jiraiya...
BTW, notice a patern with my speculation, First Hokage part of family, then over to the Second Hokage his brother, then back to the first line with Sarutobi, then back to the second with Yondiame, then back over again...etc..I could be totally wrong, as I might be, but then again, it would also be another reason Orochimaru wasn't picked,
Hopefully everything will be revealed in due course... Until then, speculate on!
- Reason -