Johnny And Susan Storm Are The Children Of Tony Stark And Steve Rogers
Because there's so doubt that Steve Rogers and Tony Stark belong together, but they've also got to have some kids too.
So they may have had some rough beginnings, but Tony Stark and Steve Rogers come to make an absolutely adorable couple. Superhusbands, even.
Enter Susan and Johnny Storm.
They are also both incredibly smart - Susan worked as Victor Von Doom's chief genetics researcher while Johnny had at one point been employed by NASA - so they certainly inherited Tony's brains. The only difference is that Susan uses her intelligence and skills more seriously, a propriety that I can imagine Steve would approve of, and Johnny uses his recklessly like Tony.
Almost everything about Johnny's reckless, fun-loving playboy personality is reminiscent of Tony - the playboy element being from before he settled down with the good Captain, of course - and Susan clearly inherited Steve's personality. In the same way Steve would likely always tell Tony what to do, both because he cares for Tony's safety as well as he knows Tony is acting irrationally, Susan tells Johnny what to do: like father like daughter, and like father like son.
The Avengers lead a very dangerous life, of course...
Steve is a more active person than Tony, so he would take Johnny out for fun while Susan would do some science down in the lab with Tony. Johnny's constantly disregard for his own safety would freak Steve out each and every time, and Tony would have a conniption every time Susan brought over a potential boyfriend (or a boy who's just a friend) - meanwhile whenever Johnny brings home the flavour of the week, Tony would give him a high five.
Johnny would undoubtedly borrow both Steve's bike and Tony's cars:
So what do you think? Johnny and Susan = offspring of Iron Man and Captain America?
And can you imagine if their 'powers' come to them as teenagers, the way they will in the new movie? Tony and Steve would certainly have their hands full.