Citation

Medland SE, Wright MJ, Geffen GM, Hay DA, Levy F, Martin NG, Duffy DL. Twin Res. 2003; 6(2): 119-130.

Affiliation

Genetic Epidemiology Unit, Queensland Institute of Medical Research, 300 Herston Road, Brisbane, Queensland 4029, Australia. sarahMe@qimr.edu.au

Copyright

(Copyright © 2003, Australian Academic Press)

DOI

10.1375/136905203321536245

PMID

12723998

Abstract

It has been suggested that twinning may influence handedness through the effects of birth order, intra-uterine crowding and mirror imaging. The influence of these effects on handedness (for writing and throwing) was examined in 3657 Monozygotic (MZ) and 3762 Dizygotic (DZ) twin pairs (born 1893-1992). Maximum likelihood analyses revealed no effects of birth order on the incidence of left-handedness. Twins were no more likely to be left-handed than their singleton siblings (n = 1757), and there were no differences between the DZ co-twin and sibling-twin covariances, suggesting that neither intra-uterine crowding nor the experience of being a twin affects handedness. There was no evidence of mirror imaging; the co-twin correlations of monochorionic and dichorionic MZ twins did not differ. Univariate genetic analyses revealed common environmental factors to be the most parsimonious explanation of familial aggregation for the writing-hand measure, while additive genetic influences provided a better interpretation of the throwing hand data.

Language: en