What is their problem? 

How old were you when your parents started letting you stay home alone? I was about 10 or 11 when I could stay home by myself for a couple of hours at a time. My sister and I still had a babysitter if my parents were out for the night, but I was way too cool for that by then. I spent the entire time playing Tetris on my flip phone to make it clear that I was too old to have a babysitter, and that her presence was strictly a formality. 

I spent a week on my own away from my parents when I was 15 on a school trip, albeit with my teacher and other parents. Even though it can be hard for teens to be away from their families for more than a couple of days at a time, they need to learn to function independently of their parents. They learn a lot about themselves by not being under somebody else’s supervision. 

By the time a kid is 17 or 18, they should be able to function without their parents full-time, because they will need to do so if they’re going to go to college. College campuses have structures in place to ensure that young adults finding their footing have the support they need to make the transition from childhood to adulthood. Even if a kid isn’t going to college, they should be able to stay at their parents’ house for a week without incident. The mom in this story thinks her 18-year-old daughter needs a babysitter, much to the chagrin of her brother, who she expects to watch her.