the whole kids thing is kinda weird... i mean, i'm 20 and single, and if the subject comes up in conversation, i'll usually just say i don't really ever wanna be a dad, but i'm not so militantly against the idea that i wouldn't consider it if i met the right girl. i mean, i'm not massively opposed to having a kid running around, i generally get on well with my younger relatives and have done since they were little, but what scares me is the ridiculous amount of influence i'd have on the kid. i mean, most of my habits, mannerisms and attitudes are a result of either picking them up off my parents, or consciously avoiding picking up other habits from my parents. the thought that EVERYTHING I DO during the kid's life up until adolesence could influence the person he/she turns out to be is a fucking scary thought.
my point is, it's something think about, but i don't think anyone could ever be totally 100% certain that they do or do not want kids - hell, probably just about every expecting mother has worries and second thoughts, and same goes for every guy on his way to get a vasectomy. what doesn't help is the people who say things like "that's what life's about, having kids, raising a family" etc.