Gillen concluded his "Secret Origin of Tony Stark" with a promised twist ending.

SPOILER ALERT: The following article contains spoilers for "Iron Man" #17, on sale now.

Kieron Gillen's "Secret Origin of Tony Stark" concludes in "Iron Man" #17 with a huge twist -- and while it may not "change the world of Iron Man forever" as the cover boasts, it certainly rewrites Tony's history in an unexpected manner. Tony Stark, long believed to be the biological son of Howard and Maria Stark, was adopted. The Starks' biological son -- the boy who got all the genetic enhancements from 451 in order to be the Godkiller's pilot -- is actually Arno Stark, who has been laid up in a hospital bed since his birth.

The choice of the name "Arno Stark" is certainly no accident -- it's the same name as Iron Man 2020, though that character's place of origin has since been revealed to be an alternate Earth. Gillen's idea to make Tony Stark a decoy for 451 not only gives his story the promised twist ending, but also builds Tony up as even more of genius than he was previously thought to be. Tony's genius and ingenuity didn't come from any kind of biological enhancements, and with his newfound also-genius brother Arno, it seems as though the Stark name is about to skyrocket in popularity.

"I think by issue #17 they'll get it. I don't mean that they don't get it now. It's more that they'll see what this story is and I'm happy with it," Gillen told CBR in June. "When he comes out the other end of this story, Tony's understanding of who he is will have been changed forever. I try to avoid saying things like that because they are overplayed, but in this case I think it's true. I also think that even the people who don't like those will be talked around by the end."

That said, Gillen's story doesn't turn over all of the cards in the writer's hand. While fans are now well aware of Tony's adoptive status, the question remains: who are Tony Stark's biological parents?

"When Kieron pitched the story, the bottom line question for us was `Does this open up the doorway to stories that are worth telling?'" Marvel Editor-in-Chief Axel Alonso told the Associated Press in an interview. "And it does. Who are Tony's parents? Will he want to know them? How will he feel about Howard? How will this affect the dynamic between father and son?"

"Iron Man" #17 is on sale now.