Genetic Differences and Malleability, Article Critique Example

In this scholarly article, Sandra Scarr and Richard A. Weinberg explores how heredity and the environment affects human cognitive abilities. Their research technique is the adoption method which allows psychologists to examine the “cognitive similarities between adopted children and their adoptive and biological parents and thus distinguish between likely genetic and environmental influences” (179). This type of research technique has been utilized in numerous studies over the last fifty years and appears to result in solid and reliable findings.


As the foundation for most of this article, the authors briefly discuss the age-old debate over nature vs. nurture. As they point out, the core of this debate is related to the suggestion that “genetic variation fixes individual and group differences” regarding how human beings behave and react in a social environment. However, the authors also state that one of the most common mistakes concerning nature vs. nurture regarding those who believe that genetics cannot be manipulated via the environment is the “failure to distinguish environmental and genetic sources of individual differences in behavior” from the role that genes and heredity play in human behavior (Scarr & Weinberg 180).


Scarr and Weinberg then proceed to discuss how the adoption model is useful in helping to discover how a child’s physical and emotional development is linked to varying biological backgrounds when the child is not related to his/her adoptive parents and in some cases when two brothers are adopted by different parents. However, because most adoption agencies tend to select parents that are members of the upper classes with exemplary socioeconomic backgrounds, the results that occur when using the adoption model are often inaccurate.


Despite the possibility of inaccurate findings via the use of the adoption model, Scarr and Weinberg nonetheless initiated two separate studies (The Minnesota Adoption Studies)–the first (Transracial Adoption Study) was done between 1974 and 1976 in order to test the idea that “black and interracial children reared by white families” would achieve equal scores on IQ tests as compared to adopted white children; the second study (the Adolescent Adoption Study) was done in 1980 in order to “access the cumulative impact of differences in family environments” on the development of children under the age of eighteen (181).

TRANSRACIAL ADOPTION STUDYIn this study, Scarr and Weinberg utilized 101 transracial adoptive families that totaled 176 children with 130 as African-American. These children were not biologically related to their adoptive parents. Scarr and Weinberg also included 143 children who were biologically related to their adoptive parents in order to compare the outcomes of the study related to IQ scores. The overall findings were that regardless of being reared by white parents, the African-American children scored just as high as their white counterparts. In fact, some of these African-American children scored quite a bit higher than the white children reared by white parents. Thus, Scarr and Weinberg concluded that “genetic racial differences do not account for a major portion of the IQ performances” (182).


In this second study, Scarr and Weinberg included 194 adopted adolescent children in 115 adoptive families, along with another group of 237 biological children in 120 other families as a comparative group. Each of the adolescents had been with their adoptive families for eighteen years and were adopted before the age of one. All of the adoptive parents were either middle or upper middle class and shared similar IQ test levels. The results of this study showed little deviation in IQs regardless of being an adopted or biological child. The main difference between this study and first one was that race did not figure into the results (184).


Lastly, Scarr and Weinberg concluded that these two Minnesota Adoption Studies clearly showed that “younger children regardless of their genetic relatedness, resemble each other intellectually,” due to sharing similar child-rearing backgrounds and environments. However, the adolescents in the second study “resembled one another only if they shared genes” (185). Therefore, adolescents as compared to younger children are less influenced by their adoptive parents and have a wider range of options related to their environments which tends to support Scarr and Weinberg’s idea that genetics can be malleable and/or manipulated by the environment. Overall, these two studies, especially the transracial study, clearly shows that people are more similar than dissimilar which helps to alleviate the old stereotype of one race being superior to another.

Works Cited

Scarr, Sandra, and Weinberg, Richard A. “The Minnesota Adoption Studies: Genetic

Differences and Malleability.” Child Development (1983): 179-186. Print.