I used to say such things to my mother 20 years ago - mostly about the children. My words were more that I wouldn't do it before 30, and then it was a maybe. (I never have wanted children, honestly).I told her any man I married would just have to be happy with that.. She swore I'd change my mind. I still don't have children. I'm 38, and will remain childless. My husband is fine with this.

But I do think most folks that say such things wind up with long-term relationships (legal marriage isn't as attractive with many) and a child or two when they are 25-30, either by accident or something changes when their mind stops developing.