What is this IMHO people keep typing?
I think the urge to procreate is a biological/evolutionary thing. It is in the nature of all species to want to procreate. As we age and the inability to procreate draws near we feel more compelled to do so. I think that is what we call the "biological clock."
For some us of though, logic supersedes biology. Those of us who chose not to have kids were able to objectively look at what is involved in procreation and realize that it is not for us. I think part of it may also be natures way to ebb population growth as our earth becomes saturated with humans.
