Honest question: how do we know they are grouchy and instead we aren't just annoying. I have a kid but kids can get on my nerves, when I'm 90 I could imagine 40

Honest question: how do we know they are grouchy and instead we aren't just annoying. I have a kid but kids can get on my nerves, when I'm 90 I could imagine 40 year olds annoying me in a similar way.