It's all in the genes
In their never ending quest to pooh-pooh the genetic influence on IQ (and everything else), a common Leftist suggestion has been that the genetic influence is "moderated" by environmental factors. Socio-economic status has been nominated as such an environmental influence. That has just had a big test and the answer found is that genes rule. Their effect is not moderated by environmental influences. Article below followed by journal Abstract
It's amusing that the authors don't want to believe their own results. They seize on things that might rescue their hypothesis. They say, for instance, that "Among twins and siblings pairs who were close in age, standardized math and reading scores increased proportionally along with mothers' years of education beyond high school"
They attribute that to an environmental influence when it could better be explained by saying that smarter mothers undertake more education. And smarter mother have smarter kids of course.
They really are pathetic in their attempt to hang on to political correctness
Genes and environment have equal influence in learning for rich and poor kids, study finds
More than 40 years ago, psychologist Sandra Scarr put forth a provocative idea: that genetic influence on children's cognitive abilities is linked to their family's income. The wealthier the family, the more influence genes have on brain development, the thinking went.
Scarr turned the nature-nurture debate on its head, proposing that how much "nature" matters varies between environments. Scarr's research has since been roundly debated and thoroughly studied by other researchers with mixed results, including reaffirmation by another American psychologist, David Rowe, in 1999.
The line of research has come to be called the Scarr-Rowe hypothesis—that parents' socio-economic status moderates genetic contributions to variation in intelligence. The thinking was that, for people of lower socio-economic status, a person's intelligence is influenced more by his or her environment than by genetics, meaning whether a child reaches full potential depends on economic standing.
I have been studying the relationship of early health conditions to subsequent school performance for 25 years and been fascinated by the role that genetics and environment play in student achievement.
A group of us set out re-examine the question: Are genetic influences on cognitive abilities larger for children raised in more advantaged environment? To get that answer, I collaborated with colleagues at Northwestern University and Stanford University.
Studying twins, siblings gives insight
We analyzed birth and school records of 24,000 twins and nearly 275,000 siblings born in Florida between 1994 and 2002. As did previous researchers who examined genetic and environmental influences of cognitive development, we focused on a very large set of twins and siblings.
Twins and siblings close in age allowed us to disentangle the role of genes and environment in development of cognitive ability. We found no evidence that social class played more of a role in educational performance for poor kids than for rich ones.
While students in the higher income groups performed better than students in the lower income groups, the relative influence of genetic and environmental differences was the same across groups. The results were published recently in the Proceedings of the National Academy of Sciences.
A complex gene-environment interaction
What is the significance of our findings? According to David Figlio, dean of the School of Education at Social Policy at Northwestern and lead author of the study, we did not confirm that environmental factors mitigate the effects of genetics on cognitive development. Environmental differences are just as important for students from affluent backgrounds as students from poorer backgrounds.
Recent research has found evidence of a difference in genetic influence on academic performance between rich and poor families in the United States, when compared with families in Australia or Western Europe.
However, our research did not replicate the U.S. findings, in part because our large data set from Florida represented a very socio-economically diverse set of families.
Our findings, however, do not contradict the overall pattern that parental socio-economic status is associated with children's cognitive development. Among twins and siblings pairs who were close in age, standardized math and reading scores increased proportionally along with mothers' years of education beyond high school.
Socioeconomic status and genetic influences on cognitive development
David N. Figlio, Jeremy Freese, Krzysztof Karbownik and Jeffrey Roth
Accurate understanding of environmental moderation of genetic influences is vital to advancing the science of cognitive development as well as for designing interventions. One widely reported idea is increasing genetic influence on cognition for children raised in higher socioeconomic status (SES) families, including recent proposals that the pattern is a particularly US phenomenon. We used matched birth and school records from Florida siblings and twins born in 1994–2002 to provide the largest, most population-diverse consideration of this hypothesis to date. We found no evidence of SES moderation of genetic influence on test scores, suggesting that articulating gene-environment interactions for cognition is more complex and elusive than previously supposed.