Brief communication: Familial resemblance in digit ratio (2D:4D)
Article first published online: 15 JUN 2009
Copyright © 2009 Wiley-Liss, Inc.
American Journal of Physical Anthropology
Volume 140, Issue 2, pages 376–380, October 2009
How to Cite
Voracek, M. and Dressler, S. G. (2009), Brief communication: Familial resemblance in digit ratio (2D:4D). Am. J. Phys. Anthropol., 140: 376–380. doi: 10.1002/ajpa.21105
- Issue published online: 3 SEP 2009
- Article first published online: 15 JUN 2009
- Manuscript Accepted: 17 APR 2009
- Manuscript Received: 17 NOV 2008
- digit ratio (2D:4D);
- family study;
- sex differences;
- prenatal testosterone
Familial resemblance in the second-to-fourth digit ratio (2D:4D), a proxy for prenatal androgen action, was studied in 1,260 individuals from 235 Austrian families. In agreement with findings from twin studies of 2D:4D, heritability estimates based on parent–child and full-sib dyad similarity indicated substantial genetic contributions to trait expression (57% for right hand, 48% for left hand 2D:4D). Because twin studies have found nonadditive genetic as well as shared environmental effects on 2D:4D to be negligible or nil, these family-based estimates in all likelihood reflect the narrow-sense (additive genetic) heritability of the trait. Directional (right-minus-left) asymmetry in 2D:4D was only weakly heritable (6%). The pattern of same-sex and different-sex parent–child and full-sib correlations yielded no evidence for X-linked inheritance. This is surprising, considering evidence for associations of male 2D:4D with sensitivity to testosterone (functional variants of the X-linked androgen receptor gene). 2D:4D was particularly strongly heritable through male lines (father–son and brother–brother correlations), thus raising the possibility that Y-linked genes (such as the sex-determining region SRY) might influence 2D:4D expression. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc.