Another not applicable.
Actually I prefer my wife's response. We would sometimes get harangued about not have children when we were much younger, my wife would fake an awful accent and say. "Dahling, I couldn't possibly have children." This inevitably got the response, "Why ever not?" To which she replied, "They might make me a grandmother." And the reply to that is, "that's the general way things work." My wife would then give her killer punch line. "I know, but I have standards, I couldn't possibly sleep with a grandfather."
A great way of saying, mind your own business.