@article{ref1,
title="Special twin environments, genetic influences and their effects on the handedness of twins and their siblings",
journal="Twin research",
year="2003",
author="Medland, Sarah E. and Wright, Margaret J. and Geffen, Gina M. and Hay, D. A. and Levy, Florence and Martin, N. G. and Duffy, David L.",
volume="6",
number="2",
pages="119-130",
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.<p /><p>Language: en</p>",
language="en",
issn="1369-0523",
doi="10.1375/136905203321536245",
url="http://dx.doi.org/10.1375/136905203321536245"
}