Parents don't matter that much

By Razib Khan | June 16, 2011 1:53 pm

Update: Stephen Dubner emailed me, and pointed me to this much longer segment which has a lot of Bryan Caplan. So it seems like the omission that I perceived was more of an issue with the production and editing process and constraints of the Marketplace segment than anything else.

End Update

I play a lot of podcasts during the day as I go about my business on my iPod shuffle. One of them is Marketplace, which has a regular Freakonomics Radio segment, where Stephen Dubner “freaks” you out with incredible facts and analysis, often with a helping hand from Steven Levitt. With all due respect to Dubner and Levitt, this still has very pre-Lehman feel. Economics has “solved” the workings of the explicit market, so why not move on to other areas which are ripe for conquest by the “logic of life?”

In any case this week’s episode kind of ticked me off just a little. It started off with the observation that college educated women apparently put 22 hours weekly into childcare today, vs. 13 hours in the 1980s. I guess fewer latchkey kids and more “helicopter parents?” Dubner basically indicates that the reasoning behind this is many parents are in a “red queen” arms race to polish the c.v.’s of their children for selective universities. This makes qualitative sense, but can we explain an increase of 9 hours on average for the ~25% of women who are college educated on striving to make sure that their kids have Wesleyan as the safety school?

Let’s put our quantitative “thinking-caps” on “freakonomics” style. ~25% of adults have university degrees. ~80% of these have public university degrees, which are usually not too selective. Some of the ~20% are from not particularly elite religious colleges. So the subset of Americans who graduated from elite universities is actually not too large a number. You can include these as natural aspirants for the best spots for their children. And a proportion of the large remainder, I’d estimate ~90%, who didn’t go to a university which required a great deal of stress and c.v. polishing would certainly strive and hope for better for their kids. But can this explain a 9 hour average rise among tens of millions of women? Doesn’t seem to pass the smell test for me. I suspect there’s a more general norm of shifting toward “high investment parenting” among the college educated cohorts.

A second aspect of the Dubner piece for Marketplace is that it totally doesn’t clue the listener in to the reality that there’s a huge behavior genetic literature which predates the interest of economics in the outcomes of parenting. ~10 years ago Judith Rich Harris came out with The Nurture Assumption, which reported the conventional finding that shared family environment only explains a small proportion of the variation in many behavioral outcomes within the population. The remainder is split between genes and “other environment” (which is a catchall category). More recently Bryan Caplan’s Selfish Reasons to Have More Kids is steeped in Harris’ work. It’s gotten a lot of media exposure, so I was surprised that Dubner didn’t mention Caplan. Instead he focused on Bruce Sacerdote at Dartmouth, who has done some research on outcomes for adoptive and biological children.

His research in this area seems about right, judging from what I know about findings in behavior genetics. In other words, he’s not a trail-blazer as much as a trail-tender. You can find a representative paper online, What happens when we randomly assign children to families?:

I use a new data set of Korean-American adoptees who, as infants, were randomly assigned to families in the U.S. I examine the treatment effects from being assigned to a high income family, a high education family or a family with four or more children. I calculate the transmission of income, education and health characteristics from adoptive parents to adoptees. I then compare these coefficients of transmission to the analogous coefficients for biological children in the same families, and to children raised by their biological parents in other data sets. Having a college educated mother increases an adoptee’s probability of graduating from college by 7 percentage points, but raises a biological child’s probability of graduating from college by 26 percentage points. In contrast, transmission of drinking and smoking behavior from parents to children is as strong for adoptees as for non-adoptees. For height, obesity, and income, transmission coefficients are significantly higher for non-adoptees than for adoptees. In this sample, sibling gender composition does not appear to affect adoptee outcomes nor does the mix of adoptee siblings versus biological siblings.

If you are an adopted kid there are some traits where parents matter a lot. For example, what religion you follow. There are some traits where parents don’t matter much at all. For example, how tall you’re going to turn out to be. And there are all the traits in between, like whether you’re going to finish college or are a regular church attender. Like most economics papers there’s a lot of fancy regressions. But a few figures and tables will give you the right idea.

The table below shows the proportion of the variation of adopted and biological children as explained by the variation of the parents. The key is to look at the ratio column. You probably wouldn’t be too surprised variation in parents’ heights can explain 10 times more of the variation in their biological children’s heights than their adopted children (ratio ~0.10). But variation in parents’ education explains 3.6 times more of the variation in their biological children’s outcomes than their adoptive children!

Overall, I agree with Dubner, Levitt, Sacerdote, Harris, and Caplan, that our society has convinced many parents that there are huge marginal returns in investment in quantity of time as opposed to quality. Falsely. By “our society,” I don’t mean specific people. Rather, I think the Zeitgeist changes from generation to generation, and some prominent people reflect that Zeitgeist. There was a time where nature was all dominant, and then the pendulum swung back to nurture during the era of the “frigid mother.” In the 1960s and 1970s despite the ascendant anti-hereditarian paradigm in the social sciences the rapid emergence of the “working mom” through female labor force participation resulted in less supervision in kids in households where both parents were working. But after this cultural “shock” perhaps we’ve adapted to the idea of women at work to the point where latchkey kids are no longer a culturally acceptable option? Or at least if you do have latchkey kids you’re negligent. Much of the reaction to the free-range kids movement seems to verge on moral panic, indicating to me that helicopter-parenting has less to do with individual rational action and more to do with group norm adherence. “It’s just what’s done!”

In hindsight I would have to admit that I was a de facto latchkey kid, and I had a stay at home mom! I Just mapped the route to and from the public library I regularly walked over the summers starting at the age of 8, alone, and it comes it at 0.8 miles. My dad was always at work, and my mom had less interest in books than I did. I do recall some young librarians asking if I was “OK” as I was carting stools back and forth because I was way too short to reach the top shelves in the adult stacks, as if I was lost, but after a while they got use to my presence and didn’t bug me (though I do recall one security guard who always seemed to be think I was up to no good as I lugged the huge oversized biogeography books around).

If this post piqued your interest, don’t stop. To understand what this all means you need to think and read about this more.

Gene-environment correlation
Gene-environment interaction
Norm of reaction

For example, if you are thinking, “OK, so Razib just explained that getting a college education is mostly genetic,” you don’t get what I am trying to say here.

CATEGORIZED UNDER: Behavior Genetics

Comments (22)

  1. Beautiful research design here. It captures essentially all of the power of more traditional adoption or twin study without nearly as much background data or the inherently exceptional circumstances invovled when there are twins.

    The strong nuture effect regarding drinking and smoking is quite interesting given the many studies showing substance abuse as a strongly hereditable trait – apparently use and abuse have different nature/nuture profiles.

  2. #1, if you’re adopted by mormons or muslims alcoholism genes aren’t going to be an issue 🙂 in other words, heritability expresses in an environmental context. so you can make a huge impact on kids from families which histories of substance abuse i’d think, by integrating them into social milieus where they’re naturally buffered and can avoid these tendencies. the main issue though is the need for a scaffolding social milieu. the reason that stuff like IQ correlations between parent and child in adoption cases drops so much in adulthood (where r = 0.19, so adoptive parents explain 4% of the variance in their adoptive children) is that when you’re adult you “select your own niche,” and then the positive feedback loops kick in.

    if adopted kids who are faculty brats could be locked up and sealed in a “small college town” their whole life the parental effect would probably persist because of social norms and expectations. as it is, here in these united states geographic mobility and “finding your own way” is taken for granted, and in this area it seems like water tends to find the lowest spot (as in, biological parental dispositions are brought to bear in adulthood as an individual self-selects a series of environments).

  3. Miley Cyrax

    Yeah, Caplan’s nature over nurture take on parenting has been all over the blogosphere (although I hate that word). Marginal Revolution has been particularly keen on it, with a lot of good comments usually accompanying. There was actually a new post today on it:

    I think the notion that parenting doesn’t matter as much as we would imagine goes against the ideals of liberal creationism and blank slatism, which strikes a nerve with a lot of people.

  4. I think the notion that parenting doesn’t matter as much as we would imagine goes against the ideals of liberal creationism and blank slatism, which strikes a nerve with a lot of people.

    i’d be willing to admit that the hours invested peaks at the tails of the political distribution. i mean, social conservatives in theory think their sons could become gay and shit.

  5. Ian

    While it looks interesting, one thing that comes to mind is how the whole cross-cultural adoption thing fits in. Rebelling against over-educated parents by not going to grad school? Spending time trying to “find” yourself instead of finishing college.

  6. While it looks interesting, one thing that comes to mind is how the whole cross-cultural adoption thing fits in. Rebelling against over-educated parents by not going to grad school? Spending time trying to “find” yourself instead of finishing college.

    yes. but this paper isn’t the linchpin, it just confirms the findings from decades of research. a lot of the adoptions aren’t cross-cultural, especially in past generations. but you get the same general trend of results. the insights here are pretty robust, even if they need to be qualified and contextualized.

  7. ryanwc

    > so I was surprised that Dubner didn’t mention Caplan.

    Well, maybe next time you hear their segment, you won’t be so surprised that you can pick it apart. It’s not just their analysis of motherhood that falls hard under scrutiny by anyone with more than a cursory familiarity with their chosen topic.

  8. #7, agreed. normally i tune them out.

  9. primary care md

    I would like to know a little more about the adoptees?Where are they from-Romania? Kids from neglected, starving or drug using parents, or very young mothers. (all higher risk kids)
    This may not be accounted for in the statistics-and we know these kids have problems later.

  10. uh, have MCAT standards dropped a lot? cuz you could actuall just read the abstract! that tells u where they are from….

    (and again people, i am not giving credence to this result because of this result. it fits with a larger set of findings about the correlations between a huge range of adopted kids and their adopted parents)

  11. AG

    I would consider educational achievement very similar to athlete training. Both talent and training matter. But which one matter more is difficult to measure. I like think the formula is like

    Achievement=Talent x effort. instead of Talent + effort.

  12. Ian

    cuz you could actuall just read the abstract

    Or failing that, at least he could have read my comment. Can’t expect people coming here to read your blog, or the original article you linked to, but not reading my comments…unthinkable!

    By the way, yeah, it was pretty obvious from what you said that this was consistent with a larger body of literature. I just thought it was a little strange – the authors of the paper raised the confounding factor of ethnicity when it came to weight (although they couldn’t think of a plausible mechanism), so not thinking of the whole cross-cultural adoption bit seemed odd to me. But then, what seems obvious to me (given my background and experience) probably isn’t obvious to everyone.

    One reason the authors might have overlooked this is the prevailing assumption that Asians and Asian-Americans are expected to be over-achievers academically. Which reminds me of Wesley Yang’s “Paper Tigers, and this response. I suspect that the “tiger mother” model represents the opposite end of the continuum. And Yang’s article highlights some of the limitations to that mode.

  13. “one thing that comes to mind is how the whole cross-cultural adoption thing fits in. Rebelling against over-educated parents by not going to grad school?”

    From anecdotal experience with many Korean adoptees, I very much doubt that this dynamic is going on. You only have to hear a few Korean adoptees with a deep Southern drawl call out to their white moms in a grocery store to get that on the inside, these kids are 100% American except to the extent that the parents seek to educate them otherwise. They were typically too young to have ever really acquired the culture of the their place of birth. If you’ve spent a lot of time around children of Korean immigrants who do have that cultural identity and then encounter a Korean adoptee who doesn’t have any of the culturally stereotypical culturally Korean tendencies it can be momentarily freaky. It is almost like meeting a transgender boy or an African immigrant (having only previously encountered African-Americans) for the first time. What you expect based upon who you see and who you are interacting with don’t quite seem to fit and it takes a moment to mentally realize that it isn’t some sort of hoax.

    I’ve seen some kids who do have identity questioning as teens (while most of the “here are your culture roots” exposure stuff happens pre-teen and tends to be abandoned by the teen years), but I can recall ever seeing, for example, the kind of deliberate underpeformance as rebellion dynamic that you will often see in ethnic minority kids from ghettos who are actually good at school in response to taunts about being an “oreo” or something equivalent. In the U.S. context, embracing an identity as an Asian-American when you have nothing inside you to go on, typically means trying to emulate some kind of “model minority” stereotype or joining a youth group in an immigrant church.

    To the extent that the experience of Korean adoptees is atypical of the general population, it really has more in common with the issues shared by kids who are adopted into a family of the same ethnicity and know they are adopted than it does with issues particular to the cross-cultural piece. For example, whatever particular talent or temperment the biological children have that runs in the family, there is a very good chance that the adopted child’s particular talent or temperment will be different, which can drive a sense of not fitting in if not handled well.

    The one possible methodological concern in this study that I see is that it is pretty atypical for a family to have both biological children and Korean adoptees in the same family. The typical adoptive family who is not on a foster child to adopted child track adopts precisely because they can’t have children. This may systemically skew the sample in ways that are hard to predict because parents who only have adopted children may have a quite different outlook on what the enterprise of parenting is all about, than parents who have both biological children and adopted children. A family that adopts kids when they already have or know that they could have biological children, for example, is probably less likely to have a helicopter parent approach than parents who have only a single adopted child or perhaps have only two adopted children and no biological children. A family that does a foreign adoption despite having kids may see parentings as more of a “missionary” activity, religious or not, and may perhaps have less monetary priorities and values that they want to impart to their kids than a childless family that may basically be looking for an heir to their own legacy.

    Given the fact that this study largely confirms a lot of other nature v. nuture research in multiple research designs, I don’t really think that parenting styles or attitudes within the pretty functional range that adopted parents fit into is actually a major factor driving these results, but the potential for skew is certainly present.

    “Selective bias” may also be a factor in Figure 3. You don’t embark on a foreign adoption when you are financially struggling. Maybe parents who seek out foreign adoptions are systemically propserous given their personal income earning potential within the random luck based spread of what similarly economically able people earn at the time that they adopt, and children, with identical capabilities revert to the mean. In the same way, sports car owners are probably momentary financial overachievers at the time they buy their cars. But, that would show up in the biological children v. adopted children comparison, so some of the difference clearly is a nature v. nuture effect.

  14. Violet

    Yes, there is a lot of evidence that parenting by itself doesn’t matter beyond a basic level of sustenance, comfort, safety and discipline. Yet, it is hard to put that in practice and knowing what constitutes as ‘basic’ level. Especially in regards to safety and discipline; these seem to be moving targets all the time.

    @ohwilleke, the abstract says that this particular set of adoptions cover a wider range of financial situations of parents than normally would happen. So, there may be a lesser bias towards parents being systemically more prosperous.

  15. SSoG

    Alright, you’ll have to forgive me, but… Helicopter parents? I’m unfamiliar with the term. Something about how much they hover, perhaps?

  16. toto

    I think Jason Malloy trotted that data out on GNXP classic long ago. I also remember seeing a couple “red lights”:

    1- Why are adoptee income/education so much lower than that of non-adoptees? Koreans aren’t exactly suppposed to be underachievers, right?

    2- Adopting parents with income <10K? Really?

    3- There is likely to be strong selection on putative adopting parents (I assume that there is some misunderstanding regarding the adopting parents with revenue < 10K), which reduces environmental variability in the sample of adopting. Mechanically, this would overestimate the relative impact of genes vs environment. However, it is possible that this sample is still quite similar to Debner and Caplan's intended target audience.

    No time to read the paper now.

  17. Koreans aren’t exactly suppposed to be underachievers, right?

    the usual explanations is korean culture. are you now asserting that korean overachievement is made in genes? 🙂

  18. toto

    Exactly ! (er, wait…)

    More seriously, I was wondering if there was some stupid confound somewhere. The difference is just huge.

  19. JL

    1- Why are adoptee income/education so much lower than that of non-adoptees? Koreans aren’t exactly suppposed to be underachievers, right?

    The non-adoptees were older on average than the adoptees. IIRC most of the former were in their 30s and most of the latter in their 20s. The income and education levels of the adoptees were above the national average, and similar to the Asian American average.

  20. JL

    The average ages for adoptees and non-adoptees were 27.82 and 33.99, respectively. The non-adoptees were also more likely to be male, which explains some of the income difference.

    From the paper:

    The adoptees in the sample have educational attainment and family income that is only modestly higher than U.S. averages. The mean years of education for the Holt adoptees is 14.75 years versus 14.11 for Asian-Americans in the NLSY and 13.57 for all other subjects in the NLSY.

    The survey measure of family income is much higher for the non-adoptees than for the adoptees: $61,000 per year versus $42,000 per year. But this huge difference narrows to $1,600 when I control for age, education, and gender.

  21. “Koreans aren’t exactly suppposed to be underachievers, right?”

    Keep in mind that the adoptees are children of people who lacked extended family resources to support them and had to be given up for adoption, and also from people who did not immigrate to a new country based on the belief that they had more opportunity there.

    In contrast, something on the order of a third to half of all Korean-Americans are medical or technical professionals or their descendants who came to the United States via a special visa for that purpose or their close relatives, and almost Korean-Americans are immigrants or descendants of immigrants who made a conscious decision to uproot their culture in search of economic opportunity that they felt more capable of exploiting than their stay at home peers.

    In other words, Korean-American immigrants were, on average, “above average” relative to the general Korean population, while Korean adoptees were, quite likely from “below average” or “average” circumstances relative to the general Korean population.

    In U.S. immigration history the only really notable significant recent waves of working class Asian immigrants to the mainland U.S. have been the railway worker era immigrants of the mid-1800s, Philippino immigrants prior to 1898 when Phillipinos were U.S. nationals, and the SE Asian war refugee and Amerasian (i.e. bastard children of unknown American soldiers) immigrants of the late 20th century.

  22. Douglas Knight

    ohwilleke, yes, but aren’t Philippinos an exception? aren’t current immigrants pretty average? Or maybe they are temporary workers who shouldn’t be counted as immigrants?


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About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


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