Bryan Caplan makes the case for having more children in The Wall Street Journal.
The main problem with parenting pessimists, though, is that they assume there's no acceptable way to make parenting less work and more fun. Parents may feel like their pressure, encouragement, money and time are all that stands between their kids and failure. But decades' worth of twin and adoption research says the opposite: Parents have a lot more room to safely maneuver than they realize, because the long-run effects of parenting on children's outcomes are much smaller than they look.
Think about everything parents want for their children. The traits most parents hope for show family resemblance: If you're healthy, smart, happy, educated, rich, righteous or appreciative, the same tends to be true for your parents, siblings and children. Of course, it's difficult to tell nature from nurture. To disentangle the two, researchers known as behavioral geneticists have focused on two kinds of families: those with twins, and those that adopt. If identical twins show a stronger resemblance than fraternal twins, the reason is probably nature. If adoptees show any resemblance to the families that raised them, the reason is probably nurture.
Parents try to instill healthy habits that last a lifetime. But the two best behavioral genetic studies of life expectancy—one of 6,000 Danish twins born between 1870 and 1900, the other of 9,000 Swedish twins born between 1886 and 1925—found zero effect of upbringing. Twin studies of height, weight and even teeth reach similar conclusions. This doesn't mean that diet, exercise and tooth-brushing don't matter—just that parental pressure to eat right, exercise and brush your teeth after meals fails to win children's hearts and minds.
Parents also strive to turn their children into smart and happy adults, but behavioral geneticists find little or no evidence that their effort pays off. In research including hundreds of twins who were raised apart, identical twins turn out to be much more alike in intelligence and happiness than fraternal twins, but twins raised together are barely more alike than twins raised apart. In fact, pioneering research by University of Minnesota psychologist David Lykken found that twins raised apart were more alike in happiness than twins raised together. Maybe it's just a fluke, but it suggests that growing up together inspires people to differentiate themselves; if he's the happy one, I'll be the malcontent...
If you enjoy reading with your children, wonderful. But if you skip the nightly book, you're not stunting their intelligence, ruining their chances for college or dooming them to a dead-end job. The same goes for the other dilemmas that weigh on parents' consciences. Watching television, playing sports, eating vegetables, living in the right neighborhood: Your choices have little effect on your kids' development, so it's OK to relax. In fact, relaxing is better for the whole family. Riding your kids "for their own good" rarely pays off, and it may hurt how your children feel about you.
I've known for years that science has shown parenting within a normal range means almost nothing but when I read what cross-adoption studies tell us I'm still in awe. Then again, we are biological animals, so why should such a thing be surprising? It's most likely because of the extent to which we've been misled, sometimes purposely and sometimes not. The Left needs environment to matter because they want to remake society and acheive equality while conservatives need to stress the importance of parenting to defend the traditional family. Though while your kids are financialy dependent on you you should be able to control their behavior, and it's sad how many parents can't, culture, their social group and genes will determine what kind of adults they become.
I made the same argument in a book review I wrote for The Occidental Observer after comparing the results of middle and lower class child rearing case studies and reviewing the exhausting and expensive regimes many of the better off subject their children to.
Environmentalist ideology has led society’s genetic elite to absurdly overestimate what a stimulating environment can do for their children, and needlessly fear a less managed existence. After giving a son or daughter the basic necessities of life and educational opportunities, further investments likely result in diminishing returns. If intelligent parents knew this, they would be less busy, have much less anxiety and possibly have more children, since doing so would be more financially feasible and enjoyable.
Caplan puts it in economic terms: as parents are artificially imposing a higher cost on themselves for each child the demand goes down.
So on this Father's Day to all readers with a decent IQ (if you read a site like this for pleasure it's likely adequate) and no hereditary diseases, criminal record or monstrous deformities, know that the most important thing you can do to have successful children is make sure they come into existence in the first place. Nature will take it from there.