Population

I came across an odd story a few weeks ago about how childlesssness is the preferred state for many, if not most people. I thought that was really weird, considering how I have been bombarded since the beginning of time with threats of impending doom due to the population explosion.
Population growth seems to have tapered off in first world countries, meaning it is still growing, just not as fast as it was. In some countries like Japan and Russia population has even started to decline, though for different reasons, I suspect.
We fight over abortion rights, argue about how many kids a family should have (Mormons say ten, Lutherans say two), spend frightful sums of money on fertility treatments and adoptions in order to have kids.
The ancient Romans had such a problem with not enough children being produced that they passed a law that required everyone to be married, or prohibited celibacy, or something.
There is something really odd going on here.
When I was younger I was never, ever, no way Jose, going to have kids. That lasted until I was about 35, whereupon I changed my tune. It could have been external circumstances, but I think it was more internal, more like a male version of a biological clock, but I really have no idea.