> People that don't want children seem somewhat selfish to me.
I've heard this before and don't understand it even a little. Not having children is like not collecting stamps for me. It doesn't interest me in the slightest. Quite the contrary, I find it irrational and self-centered when people claim their having children will improve the "way of life, genes, and moral values" of the population by adding a drop of water to a pool of over 6.5 x 10^9 humans, a number that is growing by over 250 every single minute of every day.
You can have a mich more direct effect on humanity, if that is your life's goal, by participating directly. The famous people who changed the course of history, from Aristotle to Shakespeare to Edison, did so via their work, not by making babies.