Here’s an interesting example on how intuition can go awry.  What would you guess to be the primary factor for determining whether a scientist is receptive to new and innovative scientific theories?  Education? Economic resources? Gender? None of the above! 

In Born to Rebel: Birth Order, Family Dynamics and Creative Lives (1996), a meticulously researched book that has now withstood a decade of criticism, Frank Sulloway concluded that those people who tend to cling to old paradigms, who are not confortable with new innovative scientific theories, have something surprising in common.  They tend to be firstborns. Sulloway based his conclusions on the analysis of the written positions of 3,890 persons, writers who have commented over the past several hundred years on controversial new scientific theories.

Firstborns are significantly more likely to “identify more closely with parents and authority,” and more “conforming, conventional and defensive—attributes that are all negative features of openness to experience.” [pp. 21-22.] 

Sulloway analyzed the attitudes of the writers of published commentary regarding the theory of Copernicus during the early stages of that controversy:

[I]ndividual laterborns were 5.4 times more likely than individual firstborns to support Copernicus’s claim that the earth revolves around the sun.  Copernicus himself was the youngest of four children.

[p. 38] There are many books written for a lay audience on the topic of birth order, but very few of them are carefully documented with statistical analyses.  Sulloway’s book is a shining exception to the rule.  It is a highly detailed work that presents statistics that are not merely suggestive of his conclusions, but off-the-charts in an eye-popping way.  He has carefully integrated his findings with Darwinian theory to give it a deep understanding.  Anyone reading this book will never again think of sibling rivalry as a laughing matter.  It can’t be over-emphasized the extent to which Sulloway has squeezed his data in a wide variety of ways to yield numerous fascinating findings.  I’ll start with firstborns:

“Firstborns covet status and power.  They specialize in strategies designed to subordinate rivals…. firstborns tend to be dominant, aggressive, ambitious, jealous and conservative.  At these five levels of behavior, the influence of birth order is consistent and unmistakable. [Page 79.]

Firstborns tend to be more anxious about social status and more emotionally intense. If you ask firstborns why they reject new theories of the day, however, they will rarely mention birth order.  None will tell you that they found comfort with old paradigms because of their birth order.  Sulloway’s evolutionary analysis of birth order should give us pause when considering whether an audience will be receptive to innovative theories, whether they be scientific, legal or political. Firstborns are also less likely to admit to their mistakes.  [p. 161].

There are also advantages to being a first born.  Birth order effects on IQ also show first-borns to be more “intelligent,” though the difference is not significant. 

Sulloway anticipates the objections of the many liberal minded firstborns who do exist. 

Here is his formula for how a firstborn becomes a nonconformist: “whenever one encounters a firstborn radical (and family life does occasionally produce them), such individuals are likely to have experienced substantial conflict with a parent.  Parent-offspring conflict makes honorary laterborns out of some firstborns.”  Two notable examples are Kepler and Newton [p.202]. Sulloway also suggests shyness and being the firstborn offspring of radicals as alternate routes to becoming a firstborn radical.  The parent-offspring conflict route is much more likely to happen when parents are impoverished.  The pressures of poverty deny firstborns “the usual advantages that stem from their firstborn niche.”  [pp. 123, 202].  In short, making a bee-line to one’s parents doesn’t provide the flow of resources that one might obtain in a family that is economically better off.

Now for the laterborns:

Laterborns are at a disadvantage when competing for parental resources with their older siblings.  Although they are often rebellious, “they also work hard to improve their lot through good-natured sociability and cooperation.”  Being a laterborn forges one’s character in ways that apply well-beyond the household in which one is raised.

Laterborns are more inclined than firstborns to question authority and to resist pressure to conform to a consensus.  Firstborns, in contrast, tend to endorse conventional morality.

[Pages 70-79] Laterborns are risk takers. They are more sarcastic. [pp. 114,126]. They are 18 times more likely than firstborns to lead radical political revolutions.  During the Protestant Reformation, laterborns were 48 times more likely than firstborns to become martyrs.  96% of these protestant martyrs were laterborns. [pp.268, 361.] Laterborn women are more likely than firstborns to develop loyalties with social economic groups outside of their families.

Substantial birth order effects show up in the numerous controversies associated with “new” ideas.  The greater the level of controversy, “the larger is the observed birth order effect.”  [p. 335.]  In Sulloway’s survey of 28 scientific innovations, “laterborns have typically been half a century ahead of firstborns in their willingness to endorse radical innovations.” 

How could this be that there is such a difference in outlooks between firstborns and laterborns?  Firstborns have a direct line to parental resources (e.g., food and parental attention).  As children, they will always be a bit bigger, stronger, louder and smarter than their little sibs, and they will not hesitate to utilize all of these tools to maintain that direct route to those resources.  They often assume the role of their parents’ “lieutenant” in their efforts to control resource allocation. Out of sheer necessity, laterborns must develop alternative strategies to get a fair portion of resouces.  Hence the habit of experimenting–trying alternate and creative routes.  These habitual approaches of the various types of sibs carry over into wider society when the sibs grow up.

The most moralistic and inflexible political leaders tend to be firstborns.  Where firstborns do become radicals, they “generally favor aggressive strategies.”  [p. 361].  “It is rare in history to find an advocate of nonviolent resistance, such as Gandhi or Martin Luther King Jr., who is a firstborn.”  Compromise is a special talent of middle children.   Owing to their family niche, they understand the virtues of coalitions, parliamentary procedures and government by consensus.”  [p. 362]

What about Singletons—only-borns?  If you are an only child (or if you are raised as a functional only child–far distant in age from any other siblings) you are among the least predictable subgroup in Sulloway’s family dynamics model.  The absence of siblings makes only children more susceptible to parental social values.  Only-children are not socially “pushed” by the presence of other siblings; they are “freer to occupy a variety of family niches.”  [pp. 204, 234].

Firstborn siblings are the most conservative (much more than only children).  First-borns “appear to become more socially conservative in response to the presence of younger  siblings.  Middle children tend to occupy the middle of the family spectrum and social attitudes, whereas lastborn’s are typically the most liberal family members.”  [pp. 224, 202].

Sulloway’s well-documented book is a terrific example of how human behavior can be examined by reference to triggers that become apparent only when we stop assuming that we know everything and start subjecting our behavior to a statistically rigorous scientific analysis.

In an age of generally smaller family size, Sulloway’s analysis also raises the question of whether the increase in the ratio of firstborns might account for some of America’s current conservative leanings.