Just Us 3
PLAY BUTTON: 
This beloved sitcom from 1987 has parents Moraine and Davey Justus answering the question “are you going to have any more kids?” with “nope, just us three.” And then everyone chuckles and gently shakes their heads. They aren’t having any more kids. They can’t. They won’t reveal why they can’t. They say “We would, but we can’t, let’s just leave it at that.”