I also know that I won't go forth and have children just in case I might regret missing it later in life; I don't think this is a strong enough motivation to bring more babies onto the earth. Though I suppose people do reproduce sometimes for that reason - for insurance against later regret. I think people have children for all manner of reasons- sometimes out of pure desire to nurture and witness life, sometimes out of an absence of choice, sometimes without thinking about it in any particular way. Not all the reasons to have children are the same, and not all of them are necessarily unselfish. Not all the reasons not to have children are the same, either, though. Nor are all those reasons necessarily selfish.