Handedness in the NAS/NRC Twin Study

Abstract

In 1985, a hand preference survey was completed by 973 dizygotic and 1158 monozygotic male twin pairs, all veterans of World War II. This is the largest single twin study of handedness on record. As in state-of-the-art animal research, the laterality criterion was sensitive to both direction and consistency (degree, strong or weak) of handedness. Significant pairwise concordance was shown for the total group, and for consistency and directional factors separately. However, no zygosity differences were demonstrated.

A School-based Twin Study of Handedness among Adolescents in Taiwan

“…Regardless of AE or CE model, the results suggest that the contribution of either genetic or shared environmental factors to handedness is modest at best, whereas the greatest contribution is from non-shared environmental factors. These results are consistent with many previous twin studies on handedness (Bishop, 2001;Carlier et al, 1996;Medland et al, 2003;Orlebeke et al, 1996;Ross et al, 1999). In particular, the heritability estimate of 0.16 for the directional handedness in this study is very close to that obtained in a British sample of young twins (h 2 =0.19) (Bishop, 2001), which also used a quantitative measure of hand preference.…”

“…Previous twin studies on handedness have tended to rely solely on a dichotomous classification of hand preference into right-versus left-handedness (Medland et al, 2003;Neale, 1988;Orlebeke et al, 1996;Ross et al, 1999;Sicotte et al, 1999). This approach has been criticized for being too gross to capture the variation of lateral preference and the cut-off points being too arbitrary (Satz and Green, 1999).…”

“…Among those modeling-based twin analyses, only that of Bishop (2001) restricted its study subjects to youth with a narrow age range (7-13 years). Furthermore, only one previous twin study examined the consistency of handedness (Ross et al, 1999), though as a categorical rather than a quantitative index.…”

“…In terms of heritability estimation via modeling, the results of the twin studies on handedness so far varied across different tasks or measures of handedness. Studies that showed no evidence of genetic contribution to handedness adopted a categorical approach to handedness, including one using a single overall dichotomous question (Neale, 1988), one using dichotomous question on writing-hand (Medland et al, 2003), and one using dichotomous classification on the basis of 5 tasks with five-point response (Ross et al, 1999). In contrast, studies that reported a heritability of modest magnitude for handedness either utilized a task other than writing in dichotomous format (h 2 =0.27 for throwing-hand) (Medland et al, 2003) or adopted a quantitative index of handedness (h 2 =0.19 for questionnaire-based index and 0.37 for performance-based index, though the effects did not reach statistical significance) (Bishop, 2001).…”

Determinants of handedness in twins

“…It will also be interesting to see whether handedness is related to the twin transfusion syndrome. Finally, the results invite a finer-grained analysis of data collected in meta-analyses of twin data (Sicotte, Woods, & Massiotta, 1999) and single sample twin studies (Reiss, Tymnik, KoÈ gler, KoÈ gler, & Reiss, 1999;Ross, Jaffe, Collins, Page, & Robinette, 1999) because consideration of the influence of birth order and birth weight might well change the conclusions reached in these studies. …”