ditto the 'have children' comment. I've consciously chosen not to reproduce, after having the equivalent of a 'dry run' for raising kids for a few years, and I certainly couldn't see myself ever being happy as a parent.
granted, having your own kids and raising someone else's might feel very different. I don't have experience with actual kids, but I do with dogs: my dog is always perfect and precious, whereas anyone else's dog is just annoying in a matter of hours... :-)
A bit naive, no?