Heritability of Educational Achievement in 12-year-olds and the Overlap with Cognitive Ability

Abstract

I n order to determine high school entrance level in the Netherlands, nowadays, much value is attached to the results of a national test of educational achievement (CITO), administered around age 12. Surprisingly, up until now, no attention has been paid to the etiology of individual differences in the results of this national test of educational achievement. No attempt has been made to address the question about the nature of a possible association between the results of the CITO and cognitive abilities, as measured by psychometric IQ. The aim of this study is to explore to what extent psychometric IQ and scholastic achievement, as assessed by the CITO high school entrance test, are correlated. In addition, it was investigated whether this expected correlation was due to a common genetic background, shared or nonshared environmental influences common to CITO and intelligence or a combination of these influences. To this end multivariate behavior genetic analyses with CITO and IQ at ages 5, 7, 10 and 12 years have been conducted. The correlations were .41, .50, .60, and .63 between CITO and IQ assessed at age 5, 7, 10, and 12 respectively. The results of the analyses pointed to genetic effects as the main source of variance in CITO and an important source of covariance between CITO and IQ. Additive genetic effects accounted for 60% of the individual differences found in CITO scores in a large sample of Dutch 12-year-olds. This high heritability indicated that the CITO might be a valuable instrument to assess individual differences in cognitive abilities in children but might not be the right instrument to put the effect of education to the test.In the Netherlands, nowadays, much value is attached to the results of a national test of educational achievement (CITO), administered around age 12, in order to determine high school entrance level. The results of the test are often used as an independent judgment, besides the teachers' opinion, in advising the parents on the future educational level of their child. So the CITO is used as an aid in choosing the most appropriate type of high school (e.g., academic versus technical). From a historical perspective, this attention for "independent" testing has to do with the possibilities for selection. The establisher of the CITO (Eindtoets Basisonderwijs, 2002) emphasized that this national test of educational achievement has put the effect of education in a particular school to the test besides measuring possible learning potential or cognitive abilities in children (Geldermans, 2001). It was hypothesized that success in scholastic achievement depended on the quality of the elementary school. A large number of articles in Dutch daily newspapers were dedicated to the influences of the school population and school neighborhood on the test results of the pupils. In these articles the influences of socioeconomic status (SES) and ethnic background of the majority of the children at a certain school were considered important factors to classify the school and the future success...

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