I'm sure this question has been asked before but thought I'd refresh my memory.

How old do you think is old enough for kids to start staying home by themselves? How about if they've got a younger brother/sister at home with them that they have to take care of?

My nephew/his wife have two daughters. One is 10 (will be turning 11 in a few months) and the other one is 6. My sister frequently mentions about how **** and *** needed to go somewhere and left the kids home by themselves. Now I know that this has been going on for at least two years... and continues. My sister said she doesn't see anything wrong with it because it's only for a few hours. Another time she said they only do it when/if the kids are in bed sleeping. (I know this isn't true) Their oldest daughter had ADHD and is on medication and their youngest is also ADHD and not yet on any kind of medication. I remember my sister once telling me that the other grandmother/father will no longer take care of these two because they're very active and way too much work for them.
My mom/sister kind of got into it last night because my mom started her opinion about this... What do you think?