"I was bad enough as a kid. Adding another person to the mix would've just been trouble." Maybe having a sibling would've been fun. It would've been nice having a friend when he was young that wasn't his butler. But knowing his luck with family matters, he would've ended up with an evil twin or something.
But that's just depressing so we're not going to dwell on that anymore. Tony smiles instead, changing the subject. "And speaking of trouble, you have any questions or suggestions, let us know, okay? We want this team to work out without any major problems to start us off."