Which part (of your post) is sad? I mean what do you mean by "it is sad really"?
That, we see a family that is functioning like this and seemingly unaware.
I work with young adults who are in the low average range (IQ) with other issues. They need to be explicitly told about social norms and appropriate social actions. I don't know this family but I do know that there are people who function in the way they seem to be functioning.