DEAR ABBY: I have had a falling out with my sister over her 13-year-old son, my nephew. He is generally a happy child, with everything a boy could want in moderation. My sister is separated from his father. She has primary custody, but they do have a co-parenting relationship.

My nephew respects and obeys his father, but he treats my sister like crap. He yells at her and his grandmother, constantly talks back, etc. When he tried it on me, I put him in his place with some choice words. My sister took offense, and we argued over it. I think he needs clear consequences for disrespecting adults. Instead, my sister makes excuses for why he behaves this way — “He didn’t sleep well last night. He’s upset about X-Y-Z,” etc.

I know I’m armchair parenting, but I cannot stand to see this child yell at my sister or elderly mother, and I will not tolerate that behavior toward me. We end up arguing every time I try to talk to her about it. I have stopped spending time with them because of it. Advice, please. — OLD-SCHOOL AUNTIE

DEAR AUNTIE: Your nephew may act out because he is entering his turbulent teens, and this is a phase. It could also be that his mother has yet to make him suffer the consequences for his disrespectful behavior toward you and his grandmother.

Since your sister and her ex are co-parenting, they should both be talking to their son about “respect.” His grandmother also has a tongue, and she shouldn’t tolerate her grandson’s bad behavior, either. Personally, I would handle it by avoiding the kid until he straightens up, which may take forever.