While his answer to that was, "I'm not thirty anymore," Tony was fighting a losing battle against a smile at Wanda's reassurance. He had to let it come, with a disbelieving sigh of a laugh, saving some face by directing it at Anthony. Even the endless well of protests he had at the ready in the face of optimism and any misguided support of his actions outside of keeping the Avengers functioning were quelled, silenced for now by Wanda's sincere expression and the incontestable fact that for one second Anthony seemed pretty happy to be there.
This was way out of Tony's comfort zone, though. He had to break up the fuzzy feelings by announcing, "He peed on Steve," quite seriously to Wanda, eyebrows raised as he turned back to Anthony as if he might judge the baby's actions, but the incident hadn't gotten any less funny with time. He was grinning again when he started, "Don't tell him I told you, he was very sore about it," finishing with a forced frown and his voice pitching lower and pacing changing to Steve's measured lilt.