"Censorship is the strongest drive in human nature; sex is a weak second." - Phil Kerby
I've noticed that, contrary to the usual sociobiology notions, people are rather apt to cut down on their reproductive chances in service of their memes. People in one of those dowry murder cultures don't say "Let's marry our daughters off to men who won't ask us to spend huge amounts and then quite possibly kill our daughters to get a chance at the next dowry." People in honor killing cultures don't behave like ideal Heinlein parents and say "If the man you had an affair with has good genes, we'd be delighted to take you back and help raise the kid".
Not all parents want their kids in the military, but some largish proportion do consider losing onw or more children to war to be a worthwhile sacrifice. And it seems likewise for suicide bombing.
And there are people who don't have kids because they're worried about the population explosion.
For humans, the competition between memes is at least as sharp and important as the competition between genes. I'm tempted to say that any meme which can't get people to damage their reproductve chances is too wimpy to survive in the modern world, but that's probably overdoing it.
Link thanks to dark_christian. The link is about an failed effort to keep a homosexuality-is-ok book out of school libraries. Now that I think about it, even that is an example of my premise. If homophobic societies have higher reproductive rates (plausible, but not proven, which makes it good enough for sociobiology), then one should prefer acceptance of homosexuality in other people's families.