system
A chat on subreddit /r/NoStupidQuestions
human
He's an adult and everyone will say this, but it's polite to let your family know when you're leaving, and coming home. It helps everyone else plan around meals, and outings, etc. 

It's also just a good rule of thumb from a safety perspective to let someone know where you are and when you plan on being home.

It's not required, but it's pretty basic, respectful communication for the people you are living with.
gpt
I agree to all of that, but just add that sometimes it feel natural for one side and overprotective from another.  


All depend of what is the situation of the familly : does he have a choice to live elsewhere for exemple.