Dear Abby: Lung cancer killed my mother, and rude people keep asking if she smoked

Without answering their rude question, I explain that my mother had a rare, slow-growing type of cancer that afflicts nonsmokers (which is true). Am I overreacting to this insensitive question, or is there something I’m missing? And is there a better way to answer so that people realize it doesn’t matter?

P.S. I would normally call my mother with questions like this. — MOTHERLESS DAUGHTER