Thursday, January 14, 2010

Environment Plays Key Role in Developing Reading Skills, Study Finds.

A new study of twins is the first to demonstrate that environment plays an important role in reading growth over time. (Credit: iStockphoto/Ekaterina Monakhova)
Source: ScienceDaily
ScienceDaily (Jan. 14, 2010) — While genetics play a key role in children's initial reading skills, a new study of twins is the first to demonstrate that environment plays an important role in reading growth over time.
The results give further evidence that children can make gains in reading during their early school years, above and beyond the important genetic factors that influence differences in reading, said Stephen Petrill, lead author of the study and professor of human development and family science at Ohio State University.
"We certainly have to take more seriously genetic influences on learning, but children who come into school with poor reading skills can make strides with proper instruction," Petrill said.
"The findings support the need for sustained efforts to promote reading development in children that take both genetic and environmental influences into account."
While other studies have shown that both genetics and environment influence reading skills, this is the first to show their relative roles in how quickly or slowly children's reading skills improve over time.
The study appears online in the Journal of Child Psychology and Psychiatry.
The study participants were 314 Ohio twins participating in the Western Reserve Reading Project. This study included 135 identical twins and 179 same-sex fraternal twins.
The twins began the study when they were in kindergarten or first grade and were assessed in their homes when they enrolled, and annually for the next two years.
At each home visit, the twins were given a 90-minute battery of reading-based measures. Among other things, the tests measured word and letter identification, the ability to sound out words, and the speed at which children could name a series of letters.
The researchers compared how twins scored on the tests and then used a statistical analysis to determine how much growth in their performance could be explained by genetics and how much by environmental factors.
Environmental factors include everything the children experience -- how they are cared for by their parents, how much they are read to, the neighborhood they live in, nutrition and their instruction in schools, among other factors.
The findings showed that when children start out reading, both genetics and environment play a role in readings skills, depending on the skills assessed. For word and letter identification, genetics explained about one-third of the test results, while environment explained two-thirds. For vocabulary and sound awareness, it was equally split between genetics and environment. For the speed tests, it was three-quarters genetic.
But when the researchers measured growth in reading skills, environment became much more important, Petrill said.
For reading skills that are taught, such as words and letters, the environment is almost completely responsible for growth. For awareness of sounds in reading, about 80 percent of growth was explained by the environment. Speed measures were the only ones where genetics still played a large role.
"Regardless of where children start as far as reading skills, and the impact that genetics and environment had on their initial skills, we found that their environment had an impact in how fast or how slowly those reading skills developed," Petrill said.
Petrill emphasized that a child's environment is much more than just the instruction he or she receives in school. However, instruction is likely a key part of how reading skills grow over time.
Petrill said much more research needs to be done examining the roles of genetics and the environment in shaping how children learn to read.
"We believe that both factors play a role in reading, which is very similar to what researchers find in health issues such as heart disease and obesity," Petrill said. "But we know a lot more about the relative impacts of genetics and environment on the biological systems that influence heart disease than we do in reading."
For example, people can change their environment to help lower their risk of heart disease, no matter their genetic susceptibility to the disease, he said.
Petrill said he hopes we can do the same to help children improve their reading.
"Understanding the causes of why kids differ in reading skills, and the roles of genetics and environment, could help us understand how to teach them better," he said.
Story Source:
Adapted from materials provided by
Ohio State University. Original article written by Jeff Grabmeier.
Journal Reference:
Stephen A. Petrill, Sara A. Hart, Nicole Harlaar, Jessica Logan, Laura M. Justice, Christopher Schatschneider, Lee Thompson, Laura S. DeThorne, Kirby Deater-Deckard, Laurie Cutting. Genetic and environmental influences on the growth of early reading skills. Journal of Child Psychology and Psychiatry, 2010; DOI:

Wednesday, January 13, 2010

Why Do People 'Play the Longshot' but Buy Insurance? It's in Our Genes.

New research by economists and molecular geneticists helps answer why people tend to be risk-preferring when facing longshot risks involving significant gains, such as playing the lottery. (Credit: iStockphoto/Steve Snowden)
Source: ScienceDaily
ScienceDaily (Jan. 13, 2010) — Why do some people like to take risks by playing "longshot" payoffs while, on the other hand, taking the opposite tack by buying insurance to reduce risks? A team of economists and molecular geneticists from the Hebrew University of Jerusalem and two Asian universities says the answer can be found in our genetic makeup.
The team set out to tackle the long-standing question in economic theory as to why people tend to be risk-preferring when facing longshot risks involving significant gains, such as betting on race horses, and on the other hand are risk averse when facing significant losses -- buying home or car insurance, for instance.
Many economists have struggled with this paradox, says Richard Ebstein, the Sylvia Scheinfeld Professor of Human Genetics at the Hebrew University of Jerusalem, who has probed this subject along with economists Prof. Soo Hong Chew of the National University of Singapore (NUS) and Dr. Songfa Zhong of NUS and the Hong Kong University of Science and Technology.
Ebstein notes the psychological explanation suggested by former Hebrew University psychology Professors Daniel Kahneman (a Nobel Prize laureate) and Amos Tversky, as embodied in their widely accepted prospect theory, to explain why people play the lottery and at the same time purchase insurance. Although prospect theory offers a psychological explanation for this facet of economic behavior, the underlying neurobiological and neurogenetic mechanisms have remained obscure until now, said Ebstein.
In an article just published online on PLoS ONE, Ebstein and his colleagues combined the tools of experimental economics and molecular genetics to examine the role of a well-characterized gene, monoamine oxidase A (MAOA), in predicting whether subjects are more likely to buy the lottery or insurance (or both) under well-controlled laboratory conditions.
In the experiment, 350 Han Chinese subjects were recruited in Beijing and participated in two simple choice tasks, representing proclivities to purchase lottery tickets and insurance, using real monetary incentives.
For example, the subjects were given options to keep a very small cash return upfront, with no risk, or of gambling bigger amounts that they were given upfront but with a minimal chance of actually winning and keeping the money in a lottery drawing. In the second task, concerning insurance, subjects were asked whether or not they would insure a certain but insignificant loss or would take out insurance on a larger amount with a real but low risk of actual loss.
They found that subjects with a high-activity variation of the MAOA gene are characterized by a preference for the longshot lottery and also less insurance purchasing than subjects with the low-activity genetic version. This is the first result to link attitude towards longshot risks to a specific gene. It complements other, recent findings on the neurobiological basis of economic risk taking.
As the world financial system slowly emerges from the near economic meltdown, it is worth considering, says Ebstein, that inborn biases, coded by common genetic variants, may be a major factor in fueling people's actions regarding longshot options --- with concomitant effects on financial markets.
Story Source:
Adapted from materials provided by
The Hebrew University of Jerusalem, via EurekAlert!, a service of AAAS.
Journal Reference:
Songfa Zhong, Salomon Israel, Hong Xue, Richard P. Ebstein, Soo Hong Chew. Monoamine Oxidase A Gene (MAOA) Associated with Attitude Towards Longshot Risks. PLoS ONE, 2009; 4 (12): e8516 DOI:

Tuesday, January 12, 2010

How Birth Order Affects Your Personality.

For decades the evidence has been inconclusive, but new studies show that family position may truly affect intelligence and personality.
Joshua K. Hartshorne
When I tell people I study whether birth order affects personality, I usually get blank looks. It sounds like studying whether the sky is blue. Isn’t it common sense? Popular books invoke birth order for self-discovery, relationship tips, business advice and parenting guidance in titles such as The Birth Order Book: Why You Are the Way You Are (Revell, 2009). Newspapers and morning news shows debate the importance of the latest findings (“Latter-born children engage in more risky behavior; what should parents do?”) while tossing in savory anecdotes (“Did you know that 21 of the first 23 astronauts into space were firstborns?”).
But when scientists scrutinized the data, they found that the evidence just did not hold up. In fact, until very recently there were no convincing findings that linked birth order to personality or behavior. Our common perception that birth order matters was written off as an example of our well-established tendency to remember and accept evidence that supports our pet theories while readily forgetting or overlooking that which does not. But two studies from the past three years finally found measurable effects: our position in the family does indeed affect both our IQ and our personality. It may be time to reconsider birth order as a real influence over whom we grow up to be.

Size Matters:
Before discussing the new findings, it will help to explain why decades of research that seemed to show birth-order effects was, in fact, flawed. Put simply, birth order is intricately linked to family size. A child from a two-kid family has a 50 percent chance of being a firstborn, whereas a child from a five-kid family has only a 20 percent chance of being a firstborn. So the fact that astronauts are disproportionately firstborns, for example, could merely show that they come from smaller families—not that firstborns have any particularly astronautic qualities. (Of course, firstborns may indeed have astronautic qualities. The point is that with these data, we cannot tell.)
There are many reasons that family size could affect our predilections and personalities. More children mean that parental resources (money, time and attention) have to be spread more thinly. Perhaps more telling, family size is associated with many important social factors, such as ethnicity, education and wealth. For example, wealthier, better-educated parents typically have fewer children. If astronauts are more likely to have well-educated, comfortable parents, then they are also more likely to come from a smaller family and thus are more likely to be a firstborn.
Of the some 65,000 scholarly articles about birth order indexed by Google Scholar, the vast majority suffer from this problem, making the research difficult to interpret. Many of the few remaining studies fail to show significant effects of birth order. In 1983 psychiatrists Cecile Ernst and Jules Angst of the University of Zurich determined, after a thorough review of the literature, that birth-order effects were not supported by the evidence. In 1998 psychologist Judith Rich Harris published another comprehensive attack on the concept in The Nurture Assumption (Free Press). By 2003 cognitive scientist Steven Pinker of Harvard University found it necessary to spend only two pages of his 439-page discussion of nature and nurture, The Blank Slate (Penguin), dismissing birth order as irrelevant.

New Evidence:
Even so, the case in 2003 against birth-order effects was mainly an absence of good evidence, rather than evidence of an absence. In fact, the past few years have provided good news for the theory. In 2007 Norwegian epidemiologists Petter Kristensen and Tor Bjerkedal published work showing a small but reliable negative correlation between IQ and birth order: the more older siblings one has, the lower one’s IQ. Whether birth order affects intelligence has been debated inconclusively since the late 1800s, although the sheer size of the study (about 250,000 Norwegian conscripts) and the rigorous controls for family size make this study especially convincing.
In 2009 my colleagues and I published evidence that birth order influences whom we choose as friends and spouses. Firstborns are more likely to associate with firstborns, middle-borns with middle-borns, last-borns with last-borns, and only children with only children. Because we were able to show the effect independent of family size, the finding is unlikely to be an artifact of class or ethnicity. The result is exactly what we should expect if birth order affects personality. Despite the adage that opposites attract, people tend to resemble their spouses in terms of personality. If spouses correlate on personality, and personality correlates with birth order, spouses should correlate on birth order.
Thus, the evidence seems to be shifting back in favor of our common intuition that our position in our family somehow affects who we become. The details, however, remain vague. The Norwegian study shows a slight effect on intelligence. The relationship study shows that oldest, middle, youngest and only children differ in some way yet gives no indication as to how. Moreover, although these effects are reasonably sized by the standards of research, they are small enough that it would not make any sense to organize college admissions or dating pools around birth order, much less NASA applicants.
Still, I expect people—myself included—will continue to try to make sense of the world through the prism of birth order. It’s fine for scientists to say “more study is needed,” but we must find love, gain self-knowledge and parent children now. In that sense, a great deal about who we are and how we think can be learned reading those shelves of birth order–related self-help books, even if the actual content is not yet—or will never be—experimentally confirmed.

This story was originally published with the title "Ruled by Birth Order?".