Gimme five Finger Length Ratio & Genetics
Maybe you only notice fingers when you’re admiring someone’s shiny manicure or sparkly rings. But if you look closely, you’ll see that some people have a slightly longer ring finger, while others have a longer index finger.
How it works
Finger length ratio is the length of your index finger compared to the length of your ring finger. Hormones are thought to influence finger length ratio. Some scientists believe the amount of estrogen and testosterone we’re exposed to in our mothers’ wombs can influence which digit is longer than the other. Higher testosterone exposure may be linked to a slightly longer ring finger.
The genetic link
Scientists haven’t been able to completely put their fingers on all the reasons behind whether someone’s index or ring finger is longer. However, 23andMe researchers have looked at 15 genetic markers (DNA locations) that influence finger length ratio.
Did you know?
Scientists have been trying to get their hands on clues to explain finger length differences since the late 1800’s. Over time, researchers developed a measurement system called finger length ratio. This ratio is the length of the index finger divided by the ring finger length. Generally, men tend to have lower ratios than women, which means their ring fingers are usually longer than their index fingers. Women’s ring and index fingers are often closer to equal in length.
23andMe’s Health + Ancestry Service can’t see the future written in your hands, but it can give you a closer look into your DNA. Pick up one of our kits to learn what your genes have to say about your finger length ratio.
23andMe Blog (2017, June 20). “SNPWatch: A Tale of Two Fingers.” Retrieved October 21, 2018, from https://blog.23andme.com/23andme-research/snpwatch/snpwatch-a-tale-of-two-fingers/.
Baker F. (1888). “Anthropological notes on the human hand.” American Anthropologist. 1(1):51-76.
Garn SM et al. (1975). “Early prenatal attainment of adult metacarpal-phalangeal rankings and proportions.” Am J Phys Anthropol. 43(3):327-32.
Gillam L et al. (2008). “Human 2D (index) and 4D (ring) finger lengths and ratios: cross-sectional data on linear growth patterns, sexual dimorphism and lateral asymmetry from 4 to 60 years of age.” J Anat. 213(3):325-35.
Manning J et al. (2014). “Digit Ratio (2D:4D): A Biomarker for Prenatal Sex Steroids and Adult Sex Steroids in Challenge Situations.” Front Endocrinol (Lausanne). 5:9.
Voracek M et al. (2010). “Relationships of toe-length ratios to finger-length ratios, foot preference, and wearing of toe rings.” Percept Mot Skills. 110(1):33-47.
Warrington NM et al. (2018). “Genome-wide association study identifies nine novel loci for 2D:4D finger ratio, a putative retrospective biomarker of testosterone exposure in utero.” Hum Mol Genet. 27(11):2025-2038.
Williams TJ et al. (2000). “Finger-length ratios and sexual orientation.” Nature. 404(6777):455-6.
Zheng Z and Cohn MJ. (2011). “Developmental basis of sexually dimorphic digit ratios.” Proc Natl Acad Sci U S A. 108(39):16289-94.