Did you know the length of your fingers could be connected to your drinking habits? Published in the American Journal of Human Biology, new research suggests that the length ratio between your index and ring fingers might predict how much alcohol you’re likely to consume.  

More about the study

The study focuses on what scientists call the “2D:4D ratio” – the relationship between the length of your index finger (2D) and ring finger (4D). This ratio isn’t just a random quirk of anatomy; it’s actually shaped by the amount of testosterone and estrogen you’re exposed to in the womb.

Generally, people exposed to higher levels of testosterone before birth end up with a lower 2D:4D ratio (meaning their ring finger is longer compared to their index finger), while those exposed to more estrogen have a higher ratio.

The study examined 258 university students (169 women and 89 men) with an average age of 22 years. Researchers meticulously measured participants’ finger lengths using callipers and assessed their alcohol consumption patterns using the Alcohol Use Disorders Identification Test (AUDIT), a standardised questionnaire developed by the World Health Organization.

What did the scientists find

The research team, led by scientists from Swansea University and the Medical University of Lodz in Poland, found that people with lower 2D:4D ratios (indicating higher prenatal testosterone exposure) were more likely to consume alcohol and showed higher risks for problematic drinking behaviours.

The results reveal that both men and women with lower 2D:4D ratios reported higher alcohol consumption and scored higher on the AUDIT test, which measures risky drinking behaviours. This relationship was particularly strong in men, showing what statisticians call “large effect sizes” – meaning the connection wasn’t just statistically significant, it was substantial.

“It is known that alcohol-dependent patients have very long 4th digits relative to their 2nd digits, suggesting high testosterone relative to estrogen exposure before birth. As expected, the associations were stronger for men than women,” study co-author John Manning, a professor with Swansea’s Applied Sports, Technology, Exercise and Medicine (A-STEM) research team, said in a statement.

Interestingly, the relationship was stronger for measurements taken from the right hand compared to the left. This aligns with previous research suggesting that the right hand’s 2D:4D ratio might be more sensitive to prenatal hormone exposure.

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