TY  - JOUR
PY  - 2003//
TI  - Special twin environments, genetic influences and their effects on the handedness of twins and their siblings
JO  - Twin research
A1  - Medland, Sarah E.
A1  - Wright, Margaret J.
A1  - Geffen, Gina M.
A1  - Hay, D. A.
A1  - Levy, Florence
A1  - Martin, N. G.
A1  - Duffy, David L.
SP  - 119
EP  - 130
VL  - 6
IS  - 2
N2  - 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> 
LA  - en
SN  - 1369-0523
UR  - http://dx.doi.org/10.1375/136905203321536245
ID  - ref1
ER  -