Temperament, parenting, and the so-called “non-shared environment” PART I


In the prestigious journal, Science,* researchers informed us in 1990 that  “On multiple measures of personality and temperament, occupational and leisure-time interests, and social attitudes, monozygotic twins reared apart are about as similar as are monozygotic twins reared together.”  This is old news, of course, in science, and perhaps old news to many readers.  But stop a moment and think about what this really implies. First of all, research on both siblings and twins has established strongly that 40-50 percent of the variability in personality/temperament measures is purely genetic.  This leaves 50% or more to non-genetic, or environmental influences.  Monozygotic twins by definition, have essentially identical genes, with some minor caveats.  But-just when developmental psychologists were getting used to the idea that the environment–thus nurture–controlled about half of our eventual personality traits, interests, etc. –the non-shared environment burst upon the scene.

Think again about the fact that taking the monozygotic twin pair and putting each one in a different adoptive family simply did not affect their resemblance to one another in the measured behaviors.  Hmm.  Statistics for separating genes and environment are moderately complex but the bottom line is simple. One hundred percent resemblance minus the roughly 50 % resemblance due to genetics leaves you the other fifty percent.  If a pair of twins raised together in a single family do not resemble each other more than a pair raised separately there does not seem to be an environmental effect that they shared from family.  Since the  environmental effect is not shared, it is classified as non-shared.  The general belief, at present is that no more than 5% of environmental effects are shared effects–and perhaps not that much. It might help to think of non-shared effects as effects that are unique to each twin. Continue reading

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The major role of genes in development is incontrovertible.  That I think, is nature’s gift to the newborn, the baby and the developing child.  Parents don’t teach you to cry when you are hungry, tired, or in need of comfort.  If they did, chances are they would surely teach you to cry less!  They also don’t have to spend priceless hours teaching you to smile or stand up, or hold a spoon.  Nature provides the necessary motivations.  Similarly, we know now that major temperament traits come with you right from the moment of birth.

However, since first reading about the non-shared environment concept, I have continued to shake my head in disbelief.  That children totally cared for by the immediate family in their earliest moments–learning to walk, talk,  love, hate, trust  (or not) adults that they must totally rely on, are simply unaffected by this experience is unbelievable.  This is particularly hard to accept, given that half or more of development is shaped by environment–just not the early home environment or parental bonds.  Can having a non-shared experience like a long recovery from a broken leg be 100 times more meaningful than having an icy, unloving parent?

With this is the fact that child development researchers go right on finding the effects of parenting variables on developmental outcomes.  Thousands of studies, many of them wrong, certainly, but many, many others well done and positive in findings. Continue reading

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The “Highly sensitive Person”: Hero, hype or a work in progress?

The Highly Sensitive Person in the beginning

In 1996 and 1997 Elaine Aron wrote a popular book entitled The Highly Sensitive Person and published a lengthy journal article about this personality type and its measurement scale.* ** The  27 question scale can be seen at https://www.hsperson.com/pages/test.htm.  Before constructing the scale, Aron reached out to individuals who “felt they were highly sensitive to stimulation, introverted, or quick to react emotionally” through notices at her University and publicity from a local paper.  She received over 100 responses, and from those interviewed 40 people for 3-4 hours each. From their own descriptions of their feelings and experiences, she compiled the still current  Highly Sensitive Person Scale.  Looking through it you will be struck by the fact that some questions seem closely related t0 the idea of sensitivity, but others will surprise you.  A common type of question, for example is:

                “I am easily overwhelmed by things like bright lights, strong smells, coarse fabrics, or sirens close by.”

                And– “I make it a point to avoid violent movies and TV shows.”

Others, however include such things as

                “I am deeply moved by the arts or music” and “I seem to be aware of subtleties in my environment.”

And somewhat farther afield—“I am conscientious.” And “I try hard to avoid making mistakes or forgetting things.”

At the very least the person who scores highly on this scale is both easily bothered by unwanted external stimuli and very much engaged and pleased by other sorts of stimuli.

Aron felt that these qualities all went together.  The person most naturally sensitive to the “subtleties” would also be most bothered by louder and more raucous stimuli.  Because of this, they would be most likely to feel overwhelmed at times and need to find a place to be alone and quiet. Continue reading

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Testosterone, temperament and one more scary story

From December of 2012 to March of 2013 this blog ran a series of increasingly gloomy reports about male anatomy, male testosterone and changes in the behavior of boys and men.  Summing this, the December blog reported evidence for possible and significant decreases in penis size, and major decreases in sperm count.  Both were presumed to reflect downward changes in testosterone levels.  A January blog zeroed in on changes in male behavior, noting that according to a recent writer “Women now earn 60% of Master’s degrees, about half of all law and medical degrees and 42% of all M.B.A.s.* Most important, women earn almost 60% of all bachelor’s degrees.  In a New York Times piece, Nicholas Kristof noted that as of 2010, boys were behind in reading in every single state in each levels of public school, and the grade point average for boys was 2.86 and was 3.09 for girls.  Adding to all this, Rosen noted that preference for sons was was decreasing in the United States, completely disappearing in South Korea, and falling in China and India.

A February 2013 blog focused on more widespread reports on dropping sperm counts and  on reports of decreasing testosterone levels in varied parts of the world.  It then explored the research on agents in the animal and human environment that can act as “environmental disruptors.”  These include pesticides, plasticizers (compounds added to plastics of all kinds to promote flexibility) and estrogen-like compounds of many kinds.  Changes in both behavior and reproductive functions are documented clearly for some aquatic animals in nature and others in laboratory research, There are also reports of effects on human behavior, though these are much more limited.

A March, 2013 blog noted that together with the reports on declining sperm counts there is strong factual evidence that human fertility rates have been dropping in many parts of the world, including most of Europe, where rates are well below what is needed for stable population replacement.  Rates in the US are higher, but mostly because of immigrant populations at present.  This blog then speculated that masculinity itself has been greatly discredited in the last half-century, at least in the Western world.  It has been linked  to aggression, violence, war and other lesser psychological diseases of the Western world.  A quote from an article in Psychology Today, entitled The Testosterone Curse:  Part II sums up this view emphatically, saying “Complementing the tendency to imprudent, rash or even reckless behavior are a variety of research findings indicating that high-testosterone males are more likely to be impulsive, impatient, unreliable…single-minded to the point of obsessiveness.  By nature leaning-competitively or confrontationally–toward raucous or tugged physical activities, they frequently don’t perform well academically, and (no surprise) in school one of their problems is that they may not deal very well with intellectural complexities.” ** In this blog, I concluded that the male “brand” has taken a serious beating–one that may not be beneficial to men or women.

In my final blog in this series ( also in March of 2013) I summed up my conclusions by suggesting that both biological forces and cultural attitudes were combining to disrespect, undermine, and in some quarters actively oppose the existence of masculinity.

That series came to an end last March, so what is new?  More really scary news! Continue reading

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Temperament: Men, Testosterone, Wide Faces and Hockey Players

In case “Men, testosterone, wide faces and hockey players” seems like too much in one title, lets look back on past blog findings.  About a year ago I reported Successful CEOs:  Wide faces or Extraversion?:  The first study in that blog concerned findings that faces that are wide relative to height (in bone structure, not added fat!) predict greater accomplishment among men who are the chief executive officers of their companies. A second study found, however, that this facial structure predicted that its owner would be more likely to deceive in negotiations, cheat, and generally behave more unethically.

By June, 2012, I had accumulated some further Wide Face Studies and reported on these in Temperament Updates on Wide Faces.  One report studied US President faces–a group of 29 where good frontal photos could be used–and found that the main personality factor correlating strongly with wide faces, was achievement drive. That drive would be considered to be related to aggression, so again wide faces (men only) relate to getting ahead, whether by stealth or forcefulness.  Yet another study had found that both adult males and 8 year-old boys made successful judgements of photos of target males based on width to height ratios of the faces.  That doesn’t mean that the aggression levels of the targets were known, but rather that the men and boys in the study used the ratio as a marker of aggression without any prior knowledge of the relationship. This suggested a biological basis for making such judgements.

Finally in the September 2012 blog, Temperament:  More on Faces, Asymmetry, even Optimism I cited a newer study that suggested that while women are more nurturant in a home and family setting,–doing much more in caring for children, the sick and elderly, for example, the authors note that “men appear to be more helpful than women in public activities and are also more likely to engage in heroic and risky helping. . . Combining out-group aggression with in-group helping, men are also more likely than women to die for their perceived kin in the ultimate aggressive helpfulness of suicide terrorism.”  The authors argued that men through evolution have become “competitively cooperative” in an in-group, out-group situation.  Thus our wide-faced CEOs were not only motivated to compete, but also to foster in-group cooperation that led to success.

The wide face relationship is entirely a male phenomenon, so presumptively produced by testosterone or some testosterone-related substance. A 2013 study found that “the FWHR is positively correlated with levels of testosterone in men.** Thus it is male, involves testosterone  and correlates well with achievement, aggression, corner cutting, successful careers as CEOs and US Presidents, out-group competition, and in-group cooperation.

That brings us up to 2013 and two new studies in one report.  Both suggest that these raging wide-faced males may not be hopelessly out of control in all circumstances.***  The authors of this study were concerned about recent reports of very weak findings for the wide face ratio and aggression in hockey players–a logical place to find a strong relationship.  They considered the possibility that this type of aggression might depend on some context factor or factors that no one had looked at.  Thinking that social status might be such a factor they did two experiments.  In the first they used college students, getting the ratio from frontal photos of them, and social status from a self-report measure.  Following this they were individually tested on a measure of reactive aggression.  They played against a computer but believed that they were competing with a male partner for cash prizes.

Results? Although both men and women participated equally in the experiment, there was no meaningful effect of face ratio or aggression in women, whether high or low status.  Aggression in wide-face high status men was just marginally significant, but in low status men it soared.

They then repeated this general idea in a natural hockey setting.  Pictures of the players were obtained from the sports illustrated website, and the ratio measured from this.  Player salaries, plus level (entry or standard)  were used as the status measure and penalty minutes for the same season as the aggression measure.  A total of 891 players were followed for that year.  Status was a very relative thing, of course with the lowest salary at $900,000.00 and the highest at $10,000,000.00

It turned out that contract level, salary and wide-face ratio were all significant predictors of the number of penalties per game.  Wide-face ratio alone as a predictor of aggression was significant but not a big factor alone. But–combine the face ratio and low status and the effect again is clear.  Looking only at the wide-faced, high salary and thus high status men, there is simply no effect of wide faces.  Interestingly, not all wide-faced, low status males were more aggressive.  It depended on how-wide, with aggressive effects increasing with facial width.  The authors conclude that “wide-faced men are not destined for aggressive behavior–it is only in the context of relatively low social status that wide-faced men may be particularly prone to engage in aggressive behavior.

I guess you just have to keep an eye out for wide-faced men who seem to be down on their luck–pr at ;east be sure you are in their in-group!


*  References from prior blogs will be found with those blogs.

**Lefevre, C. E., Lewis, G. J.  et al. (2013). Telling facial metrics: Facial width is associated with testosterone levels in men.  Evolution and Human Behavior, 34, 169-173.

*** Goetz, Stefan, M. M., et al. (2013)  Social Status Moderates the Relationship Between Facial Structure and Aggression.  Psychological Science 24, 2329-2334.



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