Editing Digit ratio (section)

==Explanation of the digit ratio effect==
The mechanisms by which prenatal hormones influence digit ratio are not clearly understood. Traits such as [[otoacoustic emissions]] and arm-to-trunk length ratio are also influenced by prenatal hormones, and it is postulated that [[Hox genes]] responsible for both digit and penis development play an important role in affecting these multiple traits ([[pleiotropy]]).<ref>{{cite journal | vauthors = Dickman S | title = HOX gene links limb, genital defects | journal = Science | volume = 275 | issue = 5306 | pages = 1568 | date = March 1997 | pmid = 9072822 | doi = 10.1126/science.275.5306.1568 | s2cid = 33709778 }}</ref> Direct effects of sex hormones on bone growth might be responsible, either by regulation of Hox genes in digit development or independently of such genes.

Though it is unclear why the digit ratio on the right hand should be more sensitive to prenatal hormones than that on the left hand, as indicated by the greater sex difference on the right than the left,<ref name="Honekopp_2010">{{cite journal | vauthors = Hönekopp J, Watson S | title = Meta-analysis of digit ratio 2D:4D shows greater sex difference in the right hand | journal = American Journal of Human Biology | volume = 22 | issue = 5 | pages = 619–630 | year = 2010 | pmid = 20737609 | doi = 10.1002/ajhb.21054 | s2cid = 29503255 }}</ref> these differences are not evident in dorsal measurements<ref>{{cite journal | vauthors = Kumar S, Voracek M, Singh M | title = The effects of hand preference and sex on right-left asymmetry in dorsal digit lengths among adults and children | journal = Early Human Development | volume = 153 | pages = 105293 | date = February 2021 | pmid = 33340946 | doi = 10.1016/j.earlhumdev.2020.105293 | s2cid = 229333079 }}</ref> nor bone digit ratios,<ref>{{cite journal | vauthors = Xi H, Li M, Fan Y, Zhao L | title = A comparison of measurement methods and sexual dimorphism for digit ratio (2D:4D) in Han ethnicity | journal = Archives of Sexual Behavior | volume = 43 | issue = 2 | pages = 329–333 | date = February 2014 | pmid = 24013635 | pmc = 3890058 | doi = 10.1007/s10508-013-0179-9 }}</ref><ref name="Galis_2010"/><ref>{{cite journal | vauthors = Robertson J, Zhang W, Liu JJ, Muir KR, Maciewicz RA, Doherty M | title = Radiographic assessment of the index to ring finger ratio (2D:4D) in adults | journal = Journal of Anatomy | volume = 212 | issue = 1 | pages = 42–48 | date = January 2008 | pmid = 18005121 | pmc = 2423386 | doi = 10.1111/j.1469-7580.2007.00830.x }}</ref> and it is possible that right-left differences in palmar 2D:4D may be attributed to differential placing of flexion creases.<ref name="Kumar_2019" />