Slate senior editor Emily Bazelon was online at Washingtonpost.com on Thursday, June 28, to discuss the research into birth order and intelligence. An unedited transcript of the chat follows.
Emily Bazelon: Hello and welcome—I'm online and looking forward to your questions.
Washington: The biggest flaw that I can see in the study is its assumption that sample size is equivalent to randomness. The database of 240,000 men comes from military records of men born in the late 1970s. People who come from families that volunteer for military service are not random—they're very different from the general population. Also, the study assumes that the stair-step IQ phenomenon will translate to women, because IQs are equal between the sexes. The study says the stair-step phenomenon occurs because elder of children's teaching of younger children. However, men and women differ greatly in how they are raised. Larry Summers, ex-President of Harvard, lost his job because he asserted that girls and boys are intellectually different in ways that don't relate to how they are taught. Yet the author of the study says that girls and boys are taught identically because the IQ outcomes are identical. Politicized science at best.
Emily Bazelon: Hmm, that's an interesting critique about people who are drafted v. not drafted, and one that I'd not heard before. The trick would be to show that the difference matters in terms of the way kids in different places in the birth order are treated.
About girls: This really is an open question. This study was based entirely on boys, as you know; some experts think the results translate to girls (and the press coverage tended to go along). I didn't look into this closely but I tend to share your skepticism.
Fairfax, Va.: As someone who does well on IQ tests, I've always felt that these things primarily measure how well you take tests. Is this study looking at any data that's more useful than IQ test scores?
Emily Bazelon: Ah, yes, the elephant in the middle of the room. I'm also not a big fan of IQ tests—what are they really measuring? A friend suggested this morning that maybe this study could do some good by making the IQ measure seem evern more annoying than usual, the province of bossy, uppity eldests. Ha! This study only measured IQ, so no supportive data, no.
Fairfax, Va.: Red Herring alert! Much more important than a 3-point IQ differential is whether there's anything about being a first-born or later-born that affects success and achievement and happiness. I have two sons who fit the Achievement Motivation theorists' stereotypes: first-born serious, reponsible to a fault, comfortable with adults from an early age; second takes life easier, more of an optimist, more sociable with peers. They've both done fine, have professional degrees, good jobs, great families. But they are still (in their 30s) very different people, regardless of their measured IQs. It's what you do with all your abilities (not just traditionally measured IQ) and how you find a place in your world that matters in life.
Emily Bazelon: Yes, this is the key point that I tried to make at the end of my Slate piece. I talked about a 1989 study published in Science showing that in small and medium sized families, birth order had no effect on educational attainment. So if that little IQ edge exists on average, later born kids on average are compensating for it. There's lots of different kinds of smarts!
Conestoga, Pa.: When I was in graduate school I was taught that while IQ tests didn't really measure intelligence, they were good predictors of how someone would do in school because Binet, the developer of the IQ. test, developed a test that his good students did well taking. As I understand it, we don't have a good idea of just what intelligence is, so measuring it is a bit problematic. It's probably not accurate to say that first born sons are more intelligent or smarter than their younger brothers; it is only accurate to say they do better on IQ tests.
Emily Bazelon: That's a good point. So then what do you do with the lack of evidence that first borns go further in school? Do you take it to mean that this 3-point edge doesn't really exist, or that IQ is an addled concept?
Indianapolis: So, where do you come in your family's birth order? Why does this topic rankle you so?
Emily Bazelon: I've got to tackle this one, right? I'm the oldest of four girls. I'm not sure any of us ever had our IQ tested and if I did, our parents probably made a point of not finding out the score. They were v. into the idea that it's what you make of your brain, not what's in it to start with.
I generally get annoyed when studies are hyped the way this one was—as if it was the definitive, end-of-question say on the matter. But I think I also got rankled because my youngest sister found it upsetting. She said it made her feel sort of cheated and bitter, and she is hugely successful! But I think that's what these sorts of findings so often do—divide people. And for no good reason. Statistical findings that measure averages have nothing to do with my family or anyone else's particular family.
Wheaton, Md.: I think its very obvious that, on average, the first born in large families becomes more successful. But isn't that probably more because of parents' preferences, along with their ability to pay for college. (Much harder to pay for that fouth child's tuition.)
Emily Bazelon: You may be right that parents put more attention and effort into first kids, esp in the beginning when they're also only kids. And if finances come into play, then yes they could play a role. But attention, of course, can backfire, and I'd like to hope at least that parents figure out a way to apportion money fairly among kids.
Simsbury, Conn.: The question about the nature of the sample (drawn from the military) is moot. All young men in Norway are required to register for the military, and the IQ testing is done at the time of registration. The study relied on those tests.
Emily Bazelon: aha. Good point, thanks for making it.
Washington: Because the study showed that the IQ advantage passed on to the next-oldest if the eldest brother died, I think we younger ones know what we have to do.
Emily Bazelon: now there's a dastardly effect of this study that I hadn't thought of—mass fratricide!
Washington: Interesting theory. How does it apply to twins? Also, just because someone has a higher IQ doesn't mean they have more common sense.
Emily Bazelon: Twins, in some of the literature, come out sort of screwed. The idea is that they tax their parents more, and so get less of the good stuff poured into them. But you know I feel badly even writing that, because I don't know how good those studies are, and even if they do hold up we are talking again about averages, not indiv families.
Washington: Do you think parents could influence the effectiveness of the mentoring so that it benefits the younger child more?
Emily Bazelon: Sometimes I think parents can't influence much of anything. And in theory I generally think it's better for parents to keep their noses out of sibling interactions (though believe me in practice I do that all the time).
If I was going to try to give my younger son, Simon, the chance to do more tutoring v. being tutored, I think I'd encourage him to develop some skill that my older son, Eli, doesn't have. Like music or something? But in the end I'm skeptical about how much you can orchestrate this stuff. And you know, maybe a more useful approach is to make it safe for Eli to let Simon guide him. I think oldests can get too reliant on always being the one who knows the answer, and then find it hard to let younger siblings lead, even in small ways.
St. Mary's City, Md.: Have researchers found psychological and emotional differences between first-borns and others? I'm a first-born and I know a few others, and we seem to share a need to please people. My theory is that our inexperienced parents hadn't yet developed confidence in their abilities and had high expectations of us.
Emily Bazelon: There is a big dispute in the social science lit about how birth order affects personality. If you want the "yes, it matters! take, you can take a look at Frank Sulloway's Born To Rebel. His argument is that firstborns are solid achieveers, but younger borns are the ones who change the world. For a v. smart skeptical take that birth order (and parenting) really alter or establish kids' personalities, I recommend Judith Rich Harris' The Nurture Assumption.
Just an observation: While not scientifically based, as a child care provider and teacher for many years, this news comes as no surprise. As a first-born you have your parent's undivided attention, with plenty of one-on-one time. Parents tend to me more relaxed with second, third, etc. children—there is less mystery for them about raising their child, there are more demands on them with a larger family, while they provide equal measures of love and care the intensity level is not there, and the younger sibs are allowed to develop and expolore at their own pace—which might just skew their IQ lower.
Emily Bazelon: yes, the undivided attention theory is the main one that believers in firstborn IQ advantage put forward. It's funny, though, because before the age of 12, firstborn IQs actually test LOWER in some studies. So then you have to explain why first lower, and later higher. And the theory there is that oldest's initially benefit from the extra dose of parents, but then see their environment "degraded" by the younger sibling—baby talk, playing up instead of playing down, etc. So then they backslide, but later on, after 12, the benefits of tutoring their younger sibs kick in, and they get the IQ boost.
I dunno. It's all too convoluted and complicated for me.
Alexandria, Va.: Are three IQ points statistically significant? If you take a couple thousand people who scored 112 on an IQ test and a couple thousand peopel who scored 109 on the same test, and test both groups again later, will the 112 group still score higher?
Emily Bazelon: I don't know about the results for taking a second test. But this question about the significance of the 3 point difference is coming up a lot. On an individual basis, it's meaningless: that is to say that in any one person's life, there are lots of other factors that will determine what he or she doesn't achieve, so who cares? But over a group of people, a 3 point difference does matter. In an accompanying editorial for Science, Frank Sulloway says that if Norway (where the study was done) had only two colleges, an A one and a B one, the 3 point difference would mean that an oldest child would be 13% more likely to be admitted to the A school. So there you have it, for what it's worth.
Takoma Park, Md.: As the oldest of five, I forwarded the article to my family members with a bit of tongue-in-cheek glee. I think we all have achieved very different but satisfying levels of success in our adult lives. My mother did remark, however, that the amount of time spent interacting with each of her children diminished as her family grew. She told me that she does feel that one-one-one time between parents and children does increase early knowledge and awareness early in life, and I—as the oldest—most likely got more of this type of interaction.
Emily Bazelon: Is this an argument for being the oldest, or for having smaller families? There's another side to this, though. In big families, the kids get the benefit of each other as well as their parents. And sometimes that's a v. powerful influence, in a positive way. I have to say, though, based on my own experience as 1 of 4 that it is also exhausting and chaotic!
Seaford, Del.: Did this study control for the distance between the ages of the brothers? Does it make a difference in the IQ gap if the brothers are one year apart vs. three or four years (or more)? lso, did they study what happens when there are more than two brothers? Some of this IQ boost seems to come from helping to teach the younger siblings. Did the study say anything about whether having several younger siblings would increase (or decrease) the IQ of the oldest child?
Emily Bazelon: I don't remember any controlling for age gap or family size. You can check the whole thing out at science.com.
Frederick, Md.: This study came as no surprise to me—I have known for years that I am intellectually superior to my younger brothers. I did have two questions. Has any corresponding work been done on EQ and birth order? While I have had more academic success, I will admit my youngest brother is much better at picking up girls. In addition, I was wondering if any cross-gender studies have been done?
Emily Bazelon: By EQ do you mean emotional intelligence? Not that I know of in particular, though lots on personality, which may cover this question in some way.
As for picking up girls, maybe that's got nothing to do with who's born when?
Intelligence of the parents: I find it more fascinating when two dopey people produce smart kids. I had a close friend like that. Her parents were borderline challenged. I did not even like to be around them because they were so dopey (not adopted and I am sure). She was the seventh child of eight and very smart.
Emily Bazelon: Intelligence is partially but not entirely inherited, that is genetic. Then of course there's environment, but parents don't totally or even perhaps mostly control environment. So your friend had her own genes, and influences beyond her family, and she thrived. It's pretty cool, really, to remember how limitless human potential can be.
Silver Spring, Md., Mom: My daughter was deemed gifted and talented in the Montgomery County school systems. We moved down to Florida for nine months, and in order for her to be considered for gifted and talented programs down there they required her to take an IQ test. At 10, she scored 129, but they have a plus or minus one rule, so she was approved for their gifted and talented program with a an IQ score of 130. Does three points really matter? In the eyes of God, no, but in the eyes of the "establishment" it just might.
Emily Bazelon: so there you have it—a real life example. Maybe 3 points off the G&T cut off they wouldn't have gone for.
New York: Hi Emily. Growing up in heavily Catholic Providence, R.I., during the 1960s, when the average family size was six (many families with more than four children), my anecdotal experience in no way confirms the data of the researchers. In our parochial school, as well as at others I knew of, the correlation between birth order and intelligence just wasn't borne out in the same way. I wonder aloud about a class bias in the research; older siblings in my working class milieu were caregivers, house helpers and—during teenage years—workers after school. Doting parents and deferential treatment of the sort suggested by the research had no place in our world.
Emily Bazelon: well that's the thing about the Norwegian guys being drafted: The draft is universal there, so you shouldn't see a class bias in the data. On the other hand, Norway may be different from the US in ways that matter for this birth order qu. On Huff Post, Dalton Conley has a smart post about Norway's emphasis on primogeniture. Could also affect the relevance of the finding for girls, too.
Portland, Ore.: Correlation and causation are two different things. Simply because someone finds a correlation between IQ and birth order in no way proves that one causes the other. For example, research on convenience store purchasing patterns have found a correlation between the purchase of beer and diapers. That doesn't mean that beer causes diapers, or that diapers cause beer. The purchases of both may be caused by, shall we say, "hidden factors"...
Emily Bazelon: oh so true, and almost always the limitation of social science research, AND what we forget when we're reading and thinking about it.
New York: I remember participating in a survey years ago as a first-born. I remember reading the results: we first-born were disciplined more, spanked more, etc. Is there perhaps a connection, that the discipline perhaps made us more focused on studies and thus we achieved higher IQs (pretending, of course, that I actually automatically have a high IQ because I am a first-born)?
Emily Bazelon: If you buy this IQ edge, then yes you could imagine that parental expectations help account for it. And certainly a lot of oldests have the impression that their parents were tougher on them and then let up on their younger siblings. I'm not sure, though, that I see the link to IQ edge—if the punishments and discipline were sort of knee-jerk and irrational (and I feel like I make more of those mistakes with my oldest child, probably) then they're probably not doing much good.
Philadelphia: You mentioned Judith Harris in your Slate piece. She cites studies that show that identical twins separated at birth have closer behavior than fraternal twins raised in the same household—and that adopted children have no more likely shared behavior traits with their new siblings than any two randomly chosen children—to make the point that parents have virtually zero impact on a child's behavior when it grows up. Do you agree with this take on genetics and parenting? If so, isn't all of this talk about birth order a total waste of time?
Emily Bazelon: Judy Harris is one of my favorite writers (and sources). She is so provocative and such a good needler—she really makes you rethink your assumptions! Her reading of the literature is a great humbling reminder for parents, I think, and also a reason for us to chill out. We have the idea that every little thing we do affects our kids so much, when in truth because of heredity (genes) and outside-the-family influences, we are really not so important.
I do agree with her on that, though I hesitate before throwing out ALL parental influence (maybe I just can't bear too!) And yes I do think that birth order is hugely important to us—but doesn't determine what we end up doing and how we succeed at it. If that makes sense?
Statistically significant:"An A one and a B one, the 3 point difference would mean that an oldest child would be 13 percent more likely to be admitted to the A school." Because the 3-point-higher was actually-for-real smarter and learned 13 percent more in high school, or because whoever decides on admissions looks at IQ scores and gives 13 percent credence to what is actually a random within-the-error-margin meaningless number difference?
Emily Bazelon: You know, Sulloway doesn't explain, but he's got to be making some sort of extrapolation from IQ to grades. And I wonder what the evidence is for that.
Washington: As the youngest sibling, I am nothing but grateful from the tutoring given by my older sisters. Well worth the three IQ points.
Emily Bazelon: That's a lovely way to look at it, and I'm sure us oldests wish all wish that our younger sibs would say the same thing. Though I fear mine might not!
Southern Maryland: I don't believe in astrology and birth order. My youngest sibling is the electrical engineer, so how did that happen? For both of my parents (who come from large families) the youngest two children went to college. Financially supporting the family and money were the issue, not intelligence. One of my favorite saying is that preparation plus opportunity equals luck.
Emily Bazelon: Your parents' experience is typical, accding to the research. In big families, say 7 or 8 kids, it's the youngest ones who tend to get to go to college, probably bec the family is more financially secure by the time they come along. Here's my own anecdote: My grandfather was the youngest of nine. He was the only one of them who went to college.
Washington: I would think the results of the birth order study would be hard to generalize because the subjects were all male.
Emily Bazelon: So then the question is, what about younger and older sisters is different from younger and older brothers? You could imagine some obvious differences in a study about risk-taking (which is one area in which older siblings DO matter—you can check out this Slate piece about that if you want http://www.slate.com/id/2141628/). Older brothers might be more likely to take younger brothers out drinking, maybe, since adolescent boys in general tend to act out more. I'm not sure I get how the difference btwn brothers and sisters would matter for IQ scores, though.
Only children?: Does the study say anything about only children? We have most of the same benefits as first-borns, except with even more undivided attention and without the experience of "teaching" younger siblings. I'm curious as to how that shakes out in studies like this.
Emily Bazelon: This study was all about siblings, so I'm not seeing any only child findings.
Silver Spring, Md., Mom:... No maybe about it. She would not have qualified for Gifted and Talented in the state of Florida if she has scored 3 points below the required score of 130 on her IQ test, even though I presented them with a Maryland State assessment that said she, as a sixth-grader, was reading at a 12th-grade level and doing math at an eighth-grade level.
Educators get very wrapped up in scores, and labels and in profiling. My daughter is bright, articulate, African American, and I have had to be her biggest champion in proving that she has the legitimate intelligence to back up her high IQ score. My advice: Play the game and stay up on everything related to your children, but let your kids know that it's just part of the game.
Emily Bazelon: That is both good advice and also such a hard double role to play, or at least I find it to be that way. Kids are so smart and perceptive; mine can tell I think when I really care about something, even when I'm trying to downplay it.
Washington: Although older siblings get more parental attention when they are younger, younger siblings get more attention when they are older. That was clearly the case with me as my four older siblings left home. If environment influences IQ, wouldn't that have an impact? Or would you say that IQ is developed in early childhood?
Emily Bazelon: IQ is somewhat plastic—it can change over time. So if the parental attention is really the determining factor, then you'd expect some bump later. Butagain I'm skeptical that it's so simple; it seems much more likely to me that lots of different factors influence how our brains develop.
Bethesda, Md.: I think there's a danger (mostly academic) to some non-firstborns in this study, much like the one girls still face in many schools when it comes to math and sciences. Younger siblings now can dismiss any slight midunderstanding they have in school as deficiency in intelligence because of their birth order, which they can't control. Or teachers could dismiss younger siblings as inferior to their older sisters/brothers. Don't you think this study might do more harm than good? Also: Any information on sibling intelligence/IQ scores when the older & second-oldest siblings are of different genders? How about only children?
Emily Bazelon: well I hope the results aren't taken so seriously and literally, because just as with affirmative action, it's wrong to assume that the kid standing in front of you embodies the averages that are out there. She's her own person, and she's got nothing to do with the generalizations about the group she's part of.
This only children question seems like a huge one—I am goign to have to write a separate piece about it!
Emily Bazelon: Thanks, everyone, that was great fun, and my thanks to you for your thought provoking and excellent questions.