Association between Second to Fourth Digit Ratio with Handwriting Quality and Speed among Elementary School Children

Background Genetic impacts on handwriting legibility and speed, especially in early childhood, are not well understood. The present study used a 2D:4D ratio as a biological marker to investigate the associations between genetic factors with quality and speed of handwriting among the elementary school children. Materials and Methods: The present study used a comparative-correlational method. Participants included 109 boys and 114 girls attending second and third grades in regular elementary schools in 2019 in Golestan province, Iran. The Persian Handwriting Assessment Tool (Havaei et al. 2017), and photocopy method were used to measure handwriting performance and 2D:4D ratio, respectively. Legibility in copying and dictation, as well as the speed of handwriting, were assessed as dependent variables. Results: The results showed that boys and girls had identical age and education. Moreover, it was revealed that boys had significantly lower 2D:4D ratio in both right and left hands compared to girls (P<.001). Furthermore, a negative association was observed between right 2D:4D ratio with word space in copying (r=-.23, P<.001) as well as a significant positive association between left 2D:4D ratio with word formation (r=.13, P=.04) in the dictation of boys. Additionally, the results indicated a significant negative association between right 2D:4D ratio with word alignment in the dictation of girls (r=-.20, P=.02). No other significant associations were observed between 2D:4D ratio and handwriting performance. Finally, no significant differences were observed between boys and girls in handwriting performance. Conclusion According to the results, the 2D:4D ratio does not positively affect handwriting quality and speed in elementary school children.