He Was Actually Really Being Truthful (For Once)

Natasha looked more closely. She first saw hints of a second person in the sock poking out of the blanket at a strange angle, and the pale hand with curled-up fingers resting on Tony’s chest. Then she found a head of what looked like brown curls, tucked snugly under Tony’s arm. And eventually, a second set of sleeping breaths, slow and light.

OR

The Avengers return from months of missions to find a child fast asleep on the lounge, with Tony snoring beside him. A mystery ensues.
Is Tony Stark a father? (It looks like it!) How have they never discovered the kid until now? I mean, Iron Man has always been good at keeping secrets, but a whole CHILD?