The little TARDIS-growing-debate-thing isn't something he's going to jump into, between them and all. Though, while he's at it... he plays a little with the coral on his desk, keeping an arm wrapped around Ianto. Maybe someday.
"Yeah, I can do steak, burnt-free!"
He rolls his eyes and hmphs. "I am a parent-- but I don't think I ever talked to her like that. That wouldn't've gone over well." He laughs at that and gives Ianto a look. "You need to eat more vegetables!"