They may be honest when they express themselves initially, but their revealed preference later ends up being very tragic. I know several women, and others who are friends of my wife, that did the "I don't want kids" routine only to realize that this was a huge mistake and enter the dating market at 37 to find nothing but a wasteland. People can pretend that their own reason can override their biological reality, but only to a point. "I don't want to have kids" means you die alone. Eventually people realize this.