Tony Stark is not Howard Stark’s biological son and is in fact, adopted. Crazy right? What’s crazier is he has a brother who is smarter than he is, though I’m sure Tony would disagree wholeheartedly. Arno Stark is the biological son of Howard and Maria Stark, sort of. Here’s the story:
While Maria Stark was carrying her and Howard’s first child she began having issues with the pregnancy and doctor’s told her their child may not survive. This prompted Howard Stark to travel the world in search of a cure for his unborn son. Desperate, Howard happened upon Rigellian Recorder 451 who was captured by an alien race known as the Grays. Rigellian Recorders were created by the space colonizing race, the Rigellians, for the sole purpose of finding new territory to colonize and reporting back to the Rigellians. Howard helped 451 escape on the grounds that he would help his unborn child. 451 agreed because he believed this child would be the one who would advance the growth of humanities technological prowess, protect the Earth, and be able to control the Godkiller, a massive suit of armor built to battle the Celestials. 451 engineered the baby’s DNA with Kree technology to modify the way he thinks and made him the sole pilot of the Godkiller.
Before the baby was born, Howard discovered his child had a genetic clock that would kill him and was set to go off when the baby was an adult. In order to diffuse the clock, Howard Stark was forced to develop a biococktail that would interfere with the clock but there were consequences for the yet to be born baby. The biococktail made the baby sick and resulted in him never being able to breath without an artificial lung. After Arno was born, Howard and Maria decided he would be safer hidden in a Hospice controlled by the Maria Stark Foundation. Fearful that 451 would discover his interference with Arno’s genetics, Howard and Maria decided to adopt a child, that child was Tony Stark.
Tony would not discover the existence of his foster brother Arno for another four decades or so after his own run-in with Rigellian Recorder 451. When Tony discovers his brother he goes to meet him at the Maria Stark Foundation Hospice.
Arno was delighted to finally meet Tony and they discussed a lot. Upon discovering 451 was gone, Arno was relieved and told Tony about his desires to help fix the Earth, Tony agreed and wanted to help. Tony developed an exoskeleton for Arno to be able to walk and breath normally. Together the two brothers worked to transform and rebuild the old and rundown Mandarin City into the technologically advanced, Utopian city of Troy but there was opposition from the Rings of Mandarin that wanted to destroy the Stark boys. The rings began finding hosts to attack both men and destroy the new city they built.
When the events started occurring, the Stark brothers banded together, and with the help of Troy’s Trojan Guard (a group of Iron Man armors built to protect the city), Tony and Arno were able to defeat the rings. Tony decided the city would never be safe as long as he remained so he left the care and protection of Troy in the hands of his brother Arno.