I just had a total brain fart.
Papa Petrelli was strongly hinted not to have any powers...then there's his whole powers-stealing-thing all of a sudden. Did he always have that? Why'd he go into hiding, how did he get hurt, etc etc?
Then, it occurs to me-- oh, yeah. The Serum. Maybe he isn't a natural mutie, either...and the Peter/Sylar simularities are just coincedences. Or that the serum affects bloodlines similiarly...
I assume you're referring to the comic where he meets Linderman. Maybe he had just never touched a person with powers before he met Linderman, and didn't know he had powers until he absorbed one.