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Handedness concordance and intelligence discrepancies in identical twins.

Authors
Type
Published Article
Journal
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists
Publication Date
Volume
1
Issue
4
Pages
351–356
Identifiers
PMID: 14591415
Source
Medline
License
Unknown

Abstract

The purpose of this study was to determine if the discrepancy in measured intelligence between identical twins concordant for handedness differed measureably from the discrepancy between identical twins discordant for handedness. If handed concordant and discordant twins did differ in terms of the between twin discrepancy in measured intelligence, then one could infer that congenital factors had caused dissociation of handedness and measured intelligence within a twin set. This finding would support Nagylaki and Levy's contention that the found discordance rates for handedness in identical twins is a function of "pathogenic" congenital factors disrupting the genetically determined handedness pattern. More generally, this finding would also support Satz's model with respect to pathological shifts in handedness due to brain insult either in utero or perinatally. However, in the current study, eight sets of identical twins were examined and no evidence was found to support these hypotheses. Instead, in one set where there was a marked discrepancy in measured intelligence, handedness could not be determined precisely for the twin with the lower intelligence quotient.

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