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School Achievement, Intelligence, and Personality in Twins

Published online by Cambridge University Press:  01 August 2014

B.T. Telles da Silva
Affiliation:
Department of Genetics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
M.R.L. Borges Osorio
Affiliation:
Department of Genetics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
F.M. Salzano*
Affiliation:
Department of Genetics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil
*
Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Caixa Postal 1953, 90000 Porto Alegre, RS, Brazil

Abstract

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A sample of 47 MZ and 49 DZ pairs of Brazilian twins was investigated in relation to school achievement in six specific areas of study, as well as performance in the test of Dominoes, the Differential Aptitude Tests (DAT) and Griéger's Characterological Questionnaire. Significant F-ratios (variance within DZ/variance within MZ) were observed for the school grades obtained in five of the six areas considered, as well as for their general average; the same being true for the results on the indicated measure of general intelligence, six of the eight DAT tests, and two of the characterological elements. There is a clear positive relationship between the grades earned by the twins and their performance in the Dominoes test. Achievement in Portuguese and foreign language correlates positively with DAT's Sentences; and achievement in mathematics correlates positively with DAT's Numerical Ability, Abstract Reasoning, and Clerical Speed and Accuracy. The results show an agreement with previous estimates of the genetic determination of these variables, which is to a certain extent surprising if we consider the differences in sample sizes, age, and degree of schooling of the subjects, environmental differences, and the dissimilarities which exist between the homes and school systems of USA, Europe, and Brazil.

Riassunto

RIASSUNTO

È stato studiato un campione di 47 coppie MZ e 49 DZ di gemelli brasiliani in rapporto al rendimento scolastico in sei specifiche aree di studio, cosí come in rapporto al rendimento in un certo numero di test di intelligenza e personalità. Sono stati osservati dei valori significativi di F (rapporto fra varianza nei DZ e varianza nei MZ) nei voti ottenuti in 5 delle 6 aree considerate, come pure nella media generale. Lo stesso vale per la misura dell'intelligenza generale. I risultati concordano con le precedenti stime della determinazione genetica di queste variabili, il che è in certa misura sorprendente quando si considerino le differenze per dimensioni del campione, età e grado di scolarità dei soggetti, differenze ambientali, nonché le differenze esistenti nei sistemi scolastici negli Stati Uniti, in Europa e in Brasile.

Résumé

RÉSUMÉ

Un échantillon de 47 couples MZ et 49 couples DZ de jumeaux brésiliens a été étudié par rapport aux résultats scolaires dans six domaines spécifiques, ainsi que par rapport aux résultats dans un certain nombre de tests d'intelligence et de personnalité. Des valeurs significatives de F (rapport entre variance chez les DZ et variance chez les MZ) ont été observées dans cinq des six domaines d'étude considérés, ainsi que dans l'évaluation de l'intelligence générale. Les résultats sont en accord avec les évaluations précédentes de la détermination génétique de ces variables. Ceci est surprenant si l'on considère les différences par rapport aux dimensions de l'échantillon, l'âge et le niveau scolaire des sujets, les différences de milieu, ainsi que les différences qui existent dans les systèmes scolaires aux Etats Unis, en Europe et au Brésil.

Zusammenfassung

ZUSAMMENFASSUNG

Bei einer Reihe brasilianischer Zwillingspaare (47 EZ und 49 ZZ) wurden die Schulleistungen auf sechs spezifischen Fachgebieten sowie die Ergebnisse einer Reihe von Intelligenz- und Persönlichkeitstests untersucht. Bei 5 der 6 untersuchten Fachgebiete sowie in den allgemeinen Durchschnittsleistungen konnten bemerkenswerte Resultate für F (Verhältnis zwischen der Varianz bei ZZ und der bei EZ) beobachtet werden. Das gleiche gilt für die Messung der allgemeinen Intelligenz. Die Ergebnisse stimmen mit vorhergegangenen Schätzungen der Erbbendingtheit dieser Variablen überein. Dies verwundert etwas, wenn man die Unterschiede bedenkt, die einerseits im Ausmass der Versuchsreihe, im Alter und im Schultyp der Kandidaten, andererseits in den Umweltsbedingungen sowie im Schulsystem zwischen USA, Europa und Brasilien bestehen.

Type
Research Article
Copyright
Copyright © The International Society for Twin Studies 1975

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