Sex differences in left-handedness are also evident in Scandinavia and in twins: comment on Papadatou-Pastou, Martin, Munafò, and Jones (2008)

Abstract

The lack of sex difference in left-handedness in Scandinavian countries reported by Papadatou-Pastou, Martin, Munafò, and Jones (2008) is questioned. We investigated the sex difference in left-handedness in two Finnish, one Norwegian, and one Swedish population-based sample not included in the Papadatou-Pastou et al. (2008) meta-analysis. The male-to-female odds ratio across these samples was 1.34 (95% confidence interval = 1.18, 1.51), indicating that the sex difference in left-handedness also exists in Scandinavian countries. Studies show that a similar sex difference in left-handedness is evident in twins as well. Overall, we challenge the contentions of Papadatou-Pastou et al. (a) that a lack of sex differences in left-handedness actually exists in Scandinavia or (b) that any such lack of differences could relate to extremely low levels of cultural masculinity in Scandinavian societies.