Sibling Rivalry 

The Revolution Begins at Home

Page 2 of 7

A study was recently conducted in which siblings were asked to determine who is the rebel in the family and who is the scholar. Firstborns were described as the scholars of the family and laterborns were characterized as the rebels. Similar data that I have collected since my book was published encompass information on more than 200,000 subjects. These data clearly show that laterborns, relative to firstborns, are judged to be more unconventional, more untraditional, more rebellious, and more likely to endorse a radical revolution.

I am one of the 200,000 people who took the personality measure on your Web site at I remember thinking: This is only a measure of self-representation, and how people think about themselves at a given moment in a somewhat ungrounded, abstract way. What I take more seriously are correlations between birth order and actual behavior, something you document very powerfully in your book.

My own reaction to most self-report data is exactly the same as yours, except that I feel that if I can document birth-order effects and other related effects with this kind of self-report information, then the real effects in the real world are probably bigger than those I am able to document. Remember, I was trying to see if there were any birth-order effects at all. Numerous psychologists say there are no effects worth mentioning. Yet when we measure birth-order differences within the family by asking people to compare themselves with their siblings, the effects are even larger than gender differences. If you have found anything bigger than a gender effect in personality research, you have really done well.

Let's assume you're right about the correlation between birth order and certain aspects of personality. Isn't there still something of a leap in explaining these differences in terms of family niches?

Yes, but only a small leap. Some of these explanations are already documented in the birth-order literature. For example, there are many studies showing that firstborns are more parent-identified than laterborns. So when I set forth the argument that firstborns tend to support power and authority because they are more identified with parents, this argument was not all that dependent on a leap of faith. I also argued that surrogate parenting leads firstborns to be more parent-identified and responsible--that may be a bit of a leap.

In addition, when I argued that laterborns, and middle children in particular, are the peacemakers of the family and are more likely--like Martin Luther King Jr.--to adopt nonviolent methods of protest, that has been studied in the past and has also been replicated since the publication of my book. In particular, if one asks within a family who is the peacemaker, it's usually the middle child.

In recent research I have conducted, I have been able to ask certain questions I could not ask in historical research. I can ask, for example, to what extent a subject acted as a surrogate parent toward younger siblings. Similarly, I can ask subjects how much they bossed their siblings around. Answers to these questions are related to both high conscientiousness (for surrogate parenting) and to low agreeableness (for bossiness). I therefore have documented the expected relationship that firstborns generally act as surrogate parents and that they also generally act in a bossy manner. So there is considerably less of a conceptual leap between the psychological mechanisms, which I mostly had to posit in the book, and what we know today about those behavioral relationships.

I don't actually think the theory of the psychological mechanisms lying behind these personality differences is that controversial. I think there are other matters, however, that have remained controversial. The most controversial of these is the difference between birth order effects as measured within the family, using direct sibling comparisons, and birth-order effects measured when one does not compare oneself to a sibling. It turns out that if one asks people to rate themselves--say, a laterborn--with a best friend who is a firstborn, one obtains much smaller effects than if the person were compared with his eldest brother. The effects with nonfamily members are about one-third or one-half as large as the birth-order effects one obtains if one asks people to compare themselves with their siblings.

So we have a puzzle. I have documented numerous birth-order effects in history which involve extrafamilial data. But birth-order effects outside the family, at least in contemporary personality data, are considerably smaller than within the family, so we have a bit of a contradiction. The resolution of this inconsistency lies, I think, in the fact that radical revolutions in history foster conflicts in society that generally stay within the family. Many radical revolutions have even involved, in explicit ways, the language of family dynamics. In the French Revolution, the King was the "father" of the country and the citizens were his "children." The revolutionaries saw themselves as "brothers" and "sisters," and they found themselves in conflict, just like brothers, over the need for filial loyalty and the kinds of tactics appropriate to contesting such loyalty.

So in times of radical revolution in history, there is an opportunity for within-family dynamics to become, temporarily, societywide dynamics. This would explain why one can often document larger birth-order effects in historical data than one can with self-report personality data that do not involve direct sibling comparisons.

There is research suggesting that parents, and mothers in particular, tend to act more anxious and possessive toward their first child than toward their second or later children. They are more clingy and overprotective, and they try to keep the child physically closer to them. Obviously, having a first child is a very different experience than having a second or third child. Couldn't this influence personality?

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