Science, and biology in particular, tells us that life forms reproduce for the sake of keeping their genes alive. Some species show males killing the offspring of a defeated dominant male, so that the females in the group become available for mating and the prevailing male can pass on his own genes.
The hundred-million-dollar question is this: we understand why animals do it, but what about mankind? Ask anyone around you with kids why they chose to have them. The answer depends on how honest the person is willing to be. Most will give the traditional, instinctual answer — “I want someone to carry my name, my genes” — but the harder truth, for humans and germs alike, is that every act of reproduction is done out of a fear of death. We do what we do believing we will evade death and fulfil our search for immortality somehow, through our children: our copies, our extensions.
It is the same fear that runs through existentialist thought: the discomfort of an existence with no built-in order, and the different ways people find to live with that. I go into where these ideas come from on the philosophy shelf, and into who is doing the thinking on the about page.