New York Times social manners advice columnist Philip Galanes on bragging parents:
Question: My brother and his wife constantly brag about their two children. (I mean, constantly!) Would it be evil of me to let them know that I know their teenage son was arrested recently for driving under the influence? I could slip it casually into conversation.
Answer: It’s cruel to rejoice in the misfortune of a child because you bear a silly grudge against his parents. Especially here, where the boy could have hurt himself or someone else. As for his parents’ bragging, hasn’t anyone told you that braggarts only seem self-confident? Usually, they’re overcompensating for insecurity. Play nice!