Nothing Matters So Have More Kids

The Gist: Why having kids is better for YOU.

A review of Selfish Reasons To Have More Kids by Bryan Caplan.

Our last correspondence discussed why having more kids is good for America.

This article discusses why having more kids is good for you. 

In Selfish Reasons to Have More Kids, Bryan Caplan argues we underestimate kids’ benefits and overestimate their costs.

Even if kids have high startup costs, the investment matures better than practically any other. To confirm, ask any grandparent. Caplan relates: “Unfortunately, when a couple of toddlers are running around, you lose sight of the big picture. Namely: Your kids will grow up. Your workload will lighten. By the time you have teens, you’ll wish your kids had more time for you. Once they move out, even three of them won’t seem like enough. You’ll want more phone calls and more visits—and some grandchildren while you’re still young enough to enjoy them… If you were good at being self-interested, ‘How many kids will I want when I’m sixty?’ would interest you as much as ‘How many kids do I want right now?’” The solution? Think ahead, master the marshmallow test, and get that delayed gratification!

Star Trek

Figure 1. “Hey! I’m you from the future! I’ve come back to tell you to have more kids! Is it too late to tell you not to invest in Theranos? I also need to find some humpback whales.


Like any advisable investment portfolio, having more kids spreads your risk. More kids means more possible grandchildren, more possible caretakers, more possible people to thank you on national television after winning the Super Bowl. But will it be fair to your kids to spread your resources? Caplan suggests asking, “How bad would your life have to be before you’d wish you’d never been born?”

Kids playing

Figure 2A. “Listen, Ted, I don’t think my kid is going professional. But yours has a chance. What’s it going to take for me to option your son?”


Very few regret having kids: In “the highest-quality survey ever conducted on the subject… 91 percent of parents said they would have children all over again. Only 7 percent said they wouldn’t.” Compare that to the results of a survey of childless adults over 40, where over 2/3 confessed regret.

Teds Wife

Figure 2B. Ted’s wife was less than pleased to discover that he was part of the 7 percent.


But why more kids? Because if you’ve already had one, you’ve bitten the bullet: “The main hit to parental happiness comes from child number one. Otherwise identical people who have one child instead of none are 5.6 percentage points less likely to be very happy. But once you’ve got a child, enlarging your family is practically painless. Whenever parents install another child seat in the family car, their chance of being very happy falls by a barely perceptible 0.6 percentage points. Intuitively, people sharply rearrange their lives with the arrival of their first child. They lose privacy and stop going out Saturday nights. When more children come along, however, parents’ lifestyle stays about the same.”

Swing Set

Figure 3. The swinging lifestyle has dramatically different meanings before and after kids.


More kids means you can benefit from economies of scale. The marginal cost of each additional child is lower than the previous one. One analysis of government data suggests “‘if you have two kids, ages 13 and 16, your costs as a middle-income family will be $23,000 per year’ to feed, house and clothe them. ‘However, if you have three kids, ages 11, 13, and 16, your costs will be $25,880 — in other words, the third kid is costing just $2,880 extra.’” You only need so much more house (or toys) for each additional kid, who himself can be babysat cheaper by an older sibling.


Figure 4. “If this trend continues and my calculations are correct, by our 9th kid we should be making money!”


We are having fewer kids even though having more kids is easier than ever. Americans are 3x richer than we were in 1950. “You can see our mounting riches in our homes. Compared to the tiny dwellings of the Fifties, modern families live in castles, with air conditioning.” And, what’s more, the technology of raising kids has dramatically improved: welcome to “the modern world of disposable diapers, washer dryers, microwaves, dishwashers, WalMart, and Amazon.” 

Forget resources. What about time? Jonathan Last sets the stage: In 1965, 60% of kids had a stay-at-home mom married to a working dad. That average mom spent 10.6 hours per week with her kids; that dad spent 2.6. Today, the average working mother spends almost 10 hours per week with her kids and the average working father spends over 6.5! Stay-at-home moms today spend over 17 hours with their kids. And Caplan points out that “when parents get full credit for multitasking, measured child care shoots up about 50 percent.”

But do kids require that much time?

When surveyors ask parents what one wish their kids would want from them, they usually said more time. When surveyors asked kids what they wanted from their parents, “they rarely wished for extra face time with their parents. They were much more likely to wish their parents would be less tired and stressed. The parents were completely out of touch. Virtually none guessed that kids would use their one wish to give their parents a better attitude.” 

Caplan suggests that parents’ best guide to being better parents is to take more time for themselves. Indeed, “Kid time has crowded out couple time: Parents in 2000 spent about 25 percent fewer hours with each other than they did in 1975.” Caplan argues that “before you do something for your child, try asking yourself three questions. 1. Do I enjoy it? 2. Does my child enjoy it? 3. Are there any long-run benefits?” In other words, do you like taking your kid to piano? Does your kid enjoy piano? Is your kid actually going to benefit from piano in the workforce and life? (And to drive the point home: “How would you like it if an authority figure enrolled you in a weekly piano lesson?”)


Figure 5. Strongly believing that his employees needed to be well-rounded, Stephenson’s boss forced all company workers to spend time after work everyday practicing piano, attending cotillion, writing the corporate newspaper, playing on the company softball team, and rehearsing skits for the company retreat.


All that is almost common sense (even if uncommonly practiced). But the bulk of Caplan’s book actually rests on a super-controversial premise: your biggest contribution as a parent is conception. In the nature versus nurture debate, Caplan comes down almost entirely on the side of nature. The implication is that so long as you meet some minimum standards as a parent, you can have as many kids as you’d like without worrying about affecting their outcomes.

woohoo tv

Figure 6. Convinced he had now done his part, new father Humphrey was excited to spend his children’s adolescence mining the depths of Netflix’ library. 


How does he come to this conclusion? Caplan digs deep into research surrounding adopted kids and finds that kids consistently bear much stronger resemblance to their genetic family than their adopted family.

Caplan summarizes: “A small army of researchers has compared adoptees to their relatives—biological and adopted. They find that when adopted children are young, they resemble both the adopted relatives they see every day and the biological relatives they’ve never met. However, as adopted children grow up, the story has a shocking twist: Resemblance to biological relatives remains, but resemblance to adopted relatives mostly fades away… Instead of thinking of children as lumps of clay for parents to mold, we should think of them as plastic that flexes in response to pressure—and pops back to its original shape once the pressure is released.”

Or put another way: “Think about all the times in your childhood when you got in big trouble and vowed, ‘I’ll be good from now on.’ How long did your change of heart last? A month? A week? Five minutes?”

And here’s a more mathematical explanation you can skip if you just want the results:

“It’s easy to understand what it means for nature or nurture to have zero effect. What does it mean, though, for nature or nurture effects to be ‘small’ or ‘large’? The clearest measures come from a thought experiment I call ‘Switched at Birth’: Imagine you have an identical twin, but there’s a mix-up at the hospital: A nurse accidentally switches your twin with another family’s baby. You and the strangers’ baby grow up with your biological parents. Your twin grows up with the strangers. Decades later, the hospital discovers its mistake and arranges a meeting between you, your identical twin, and your accidentally adopted sibling. To measure the effect of nature, just answer this question: Suppose you’re higher on some trait—height, intelligence, income, conservatism, you name it—than 80 percent of your peers. How high on this trait should you expect your TWIN from Switched at Birth to be? To measure the effect of nurture, just answer this question: Suppose you’re higher on some trait—height, intelligence, income, conservatism, you name it—than 80 percent of your peers. How high on this trait should you expect your ADOPTED SIBLING from Switched at Birth to be? …Intuitively, if nature didn’t matter at all, you would expect your separated twin to be average—in the 50th percentile. If nature were destiny, you would expect your separated twin to match you in the 80th percentile; Similarly, if nurture didn’t matter at all, you would expect your adopted sibling to be average; if nurture were destiny, you would expect your adopted sibling to be in the 80th percentile, just like you.”

So, what are the results? Parenting – that is to say non-genetic contribution – has little to no effect on kids’ measured intelligence, grades earned in school, the amount of school kids will complete, adult sexual behavior, divorce rate, happiness, income, criminality, number of hospital visits, and life expectancy. Studies are mixed on whether parenting affects kids’ smoking, drinking, and drug use. Parenting has a moderate effect on when daughters start having sex – but much smaller on sons. The only places where Caplan finds parenting has a strong effect are religious and political identity – but not how often kids ultimately attend services or vote.

In other words, studies suggest that if you never met your identical twin, you’d wind up having closer IQ, grades, degrees, happiness, income, criminal records, and health than those genetically unrelated people you spent all your time with growing up. You may have different religious identities – but you’d attend services on a similar schedule. 

These results are not intuitive – and certainly you’d like to think you have a much bigger impact as a parent. But what if they’re true? Read the book and closely examine the studies yourself. Caplan’s exhaustive presentation is scary in its scale.

To give you a taste, one study looked at 1,600 Korean kids adopted by a variety of American families in 1955. The result? “Neither family income nor neighborhood income increased adoptees’ academic success. If you ever thought it unfair for rich parents to buy their children’s way through school, be at peace; apparently they don’t get what they pay for.” Another study looked at 1,700 high school students across America: “If you’re in the 80th percentile of your class, expect the identical twin you’ve never met to be in the 71st. Parental effects, in contrast, were literally invisible. The GPAs of unrelated kids raised together were no more similar than strangers.’”

Or looking to Scandinavia: “Swedes have almost no financial privacy; researchers can collect your complete lifetime earnings history from tax records. One study of over 5,000 Swedish twins was therefore able to confirm that the effect of nurture on men’s income changes with age. Family has a moderate effect in your early twenties. Suppose you earn more than 80 percent of your peers. You should expect your adopted brother to make more money than 58 percent of his peers when he is twenty to twenty-two years old, and 55 percent when he is twenty-three to twenty-five years old. By the time your adopted brother reaches his late twenties, however, the effect of upbringing on income completely fades out—and remains invisible for the rest of his career. When children first become adults, their parents might find them a good job, or support them so they don’t have to work. Within a few years, however, young adults get on their own two feet, and stay there.”

Bear in mind that Caplan is an indifferent libertarian when reading this next one: “Every major twin study finds that identical twins are more alike in their sexual orientation than fraternal twins. Yet genes are far from the whole story—if you’re gay, your identical twin is usually still straight. Upbringing might make a difference, too. In surveys, adopted brothers of gay men and adopted sisters of gay women are about six times as likely to be gay as the general population. This would normally be a smoking gun, but sexual orientation remains a touchy issue. The adoption results might merely show that gays with gay adopted siblings were six times as likely to mail in their surveys.”

Ultimately, Caplan concludes “the most effective way to get the kind of kids you want is to pick a spouse who has the traits you want your kids to have.” And before you decide to spend all your time on vacation, read his citation from Judith Harris: “People sometimes ask me, ‘So you mean it doesn’t matter how I treat my child?’ They never ask, ‘So you mean it doesn’t matter how I treat my husband or wife?’ and yet the situation is similar. I don’t expect that the way I act toward my husband is going to determine what kind of person he will be ten or twenty years from now. I do expect, however, that it will affect how happy he is to live with me and whether we will still be good friends in ten or twenty years.”

Selfish reasons to have more kids

Figure 7. Click here to buy Selfish Reasons to Have More Kids. 7/10. I did not expect that the bulk of the book would be dedicated to proving that nature triumphs over nurture but it certainly has implications for parenting and the studies are worth reading. Regardless of whether you buy that specific argument, there are other selfish reasons to have more kids (spread your risk!) and the costs are overstated (economies of scale!). There is also some good data about how kids are safer than ever (only about 1 in a million chance per year your kid will be kidnapped) and happiness (“If you’re married with children, you’re [18% more] likely to be happy than if you’re single and childless. Taken too literally, the statistics imply that married couples require over a dozen kids to feel worse than childless singles.”). If you’re still not convinced, remember America!


Thanks for reading! If you enjoyed this, forward it to a friend: know anyone with kids? How about anyone who is thinking about having them? How about anyone who was once a kid?

For more, check out my archive of writings, including my review of the Tech-Wise Family, which includes 7 specific and escalating steps to spend less time with your favorite screen. 

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