Warning: SPOILERS for Avengers: Endgame
When Tony Stark first launched the MCU in Avengers: Endgame used time travel to make peace with Howard Stark, but as heartwarming as Tony's bond with his father may be, the movie may have revealed that it wasn't biological--and that Tony was adopted by Howard and Maria Stark.
As the hero who created Marvel's movie universe with the first Iron Man film, and later acted as a father figure to its youngest star, Spider-Man, it makes sense for Avengers: Endgame to use the theme of fatherhood to make peace with the past, and hand the future to a new generation. In the end, Tony Stark realized the same thing that his father did: all their brilliant inventions aside, their "greatest creations" were the children they loved. For Tony, it was his daughter Morgan. But for Howard? Well, Tony may not have been an only child after all.
As scandalous as it may sound at first, Avengers: Endgame includes an exchange that's hard to dismiss as anything but a major hint that Tony Stark was secretly adopted... just as he was in Marvel Comics.
Why Avengers: Endgame Travels Back to 1970
The evidence fans could use to estimate Tony's age and date of birth multiplied from the first Iron Man to Iron Man 2, with Howard's filmed introduction to the 1974 Stark Expo featuring a young Tony. Thankfully, Tony's S.H.I.E.L.D. file (revealed between Iron Man 2 and The Avengers) gave an exact date of birth: May 29th, 1970. Ever since then Marvel die-hards have celebrated the occasion... but the date probably wasn't kept in mind by most movie fans going into the theater to see Avengers: Endgame. If they had, one strange detail about Tony and Steve's mission into the past would have stuck out like a sore thumb.
Before they actually depart Manhattan (during the first Avengers film), it's Tony who suddenly re when the Tesseract and Hank Pym were in the same place, at the same time. The place is simple enough to grasp: Camp Lehigh, the birthplace of S.H.I.E.L.D. that Steve and Natasha visit in Captain America: The Winter Soldier. But the date is the real riddle, and Steve is less than convinced when Tony says he has "a vaguely exact" idea of the day they need to travel to. When pressed, he explains that, "I know for a fact they were there, and I know how I know."
The movie never actually revisits this line to explain... well, how Tony knows what he knows, but his encounter with his father gives a likely explanation. And it also throws a major clue that Tony's date of birth may not be what he believes.
Avengers: Endgame Hints at Tony's Birthday
It would be simple enough to say that in studying his father's work on the Tesseract, Tony noted he was working on it at Lehigh either in the months prior to his birth, or around April 7th, 1970 specifically. It also makes sense that if Howard worked with Hank Pym shortly before Tony was born, it would come up, and the dots could be connected to make an educated guess. In hindsight, it seems odd that the writers of Endgame wouldn't have Tony travel back to his actual birthday--a far cleaner point to explain his knowledge of that day, and "how he knows." But the movie may deal with that exact inconsistency when Tony and Howard actually meet.
Fans will most recall the knowing words spoken between the two Starks, but the key moment comes earlier, when the pair first step onto the Camp Lehigh elevator. Tony inquires as to the "flowers and sauerkraut" Howard is carrying, suggesting he's got "a hot date." Howard explains by revealing that "My wife is expecting... and too much time at the office." The revelation isn't Maria Stark's cravings... but Tony's reaction.
Going wide-eyed and frozen in an instant, Tony immediately asks Howard--without the slightest hint of casual conversation--"how far along" his mother must be. Howard doesn't give an exact answer, but the question is what's important here. Why would Tony possibly have to ask when Maria is due? And why would he be surprised to learn his father is bringing her flowers and sauerkraut on April 7th, a full seven and a half weeks before he was born? Whatever theories can be spun, it doesn't make any sense for Tony's sudden confusion and questioning to be due to him 'not realizing' he traveled back to a month before his birth. It's the flowers and food that stun Tony, and urge him to how far away his delivery must be.
Are we suggesting that Howard Stark 'buying Maria flowers when Tony was born' was a rare enough occasion to , and retell? Or that such a gesture was only ever made when Maria was in hospital ahead of her delivery? Well actually... that would fit with Howard's cold depictions thus far. But there may be another explanation for what Tony may be realizing, which would explain why the Howard of 1970 is far warmer than the one who raised Tony... and why the dates surrounding Tony's birth stop him in his tracks.
Was Tony Stark Adopted (Like The Comics)?
All of these questions are resolved--and the confused exchange between Tony and Howard only makes sense--once fans realize that Tony Stark was adopted all along, according to Marvel Comics. After their biological son was born with a terrible, degenerative condition, they adopted another son, Tony, and raised him without ever telling him the truth. The plot was revealed in Kieron Gillen's 2013 Iron Man comics, with the adoption and 'substitution' part of a larger alien plot. Obviously, an alien engineering Howard and Maria's child wasn't ever likely in the MCU. But Tony being adopted after the Starks' first baby turned from joy to tragedy? That's definitely within the realm of possibility.
When comparing Endgame to previous Marvel films, a reference to Tony's birth date not quite matching Maria's pregnancy is exactly the kind of comic book nod fans expect. For the casual viewer it wouldn't even . But for the comic readers who know Tony's date of birth wouldn't match up to Maria's pregnancy at all? It's a mind-blowing, inside hint. Not only to Tony's confused discovery of his true parentage, but of the Stark sibling potentially alive and well in the MCU.
Fans probably shouldn't expect the emergence of Arno Stark, Tony's just-as-brilliant brother into the new Marvel movie universe. But the potential is there, and Marvel has turned tiny Easter Eggs into future MCU events before. Regardless of the outcome, fans will forever be able to enjoy this Endgame scene--not just for the reunion between Tony and Howard, but the subtle suggestion that Tony's adoption in the comics was honored, whether audiences realized it or not.
