A love of alcohol begins when a person is still in the womb, a new study claims.
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In determining who is predisposed to heavy drinking, researchers found that it is linked to testosterone exposure during pregnancy, which has a distinct effect on a baby’s hand development.
“It is possible that differences in alcohol consumption are set in the womb,” professor and study author John Manning, who teaches evolutionary biology at Swansea University in Wales, said in the study published in the American Journal of Human Biology, according to the Daily Mail.
The researchers surveyed more than 258 students – 169 women and 58 men – on their weekly boozing habits.
The participants’ fingers were then measured, as it is believed that the digits reveal how much testosterone or estrogen they were exposed to in the womb, determining their level of “masculinity.”
The scientists used the somewhat disputed method of gauging 2D:4D digit ratios, the discrepancy in length between the index and ring fingers.
Manning believes that having a longer ring finger compared to the index one means there was more prenatal testosterone exposure, while having a longer pointer finger was linked to a higher level of estrogen in the womb.
“Digit ratio (2D:4D) denotes the relative length of the second and fourth digits,” he explained. “This ratio is considered to be a biomarker of the balance between fetal testosterone and estrogen.”
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The test found that the heavier drinkers tended to have a “low digit ratio” – meaning their ring finger is longer than their index finger – and were therefore exposed to higher levels of male sex hormones in the womb.
From that data, Manning suggested that higher testosterone – or “prenatal sex steroid,” as the study calls it – results in increased alcohol tolerance and drinking habits.
“Enzymes in male stomachs can reduce the absorption of alcohol by 30% whereas females absorb more into the bloodstream,” he noted.
“Alcohol consumption is a major social and economic problem,” explained Manning. “Therefore, it is important to understand why alcohol use shows considerable differences across individuals.”
Manning said more studies are needed to determine more specifically how prenatal testosterone exposure and adult drinking are linked as the study sampled only students, which could represent a small group in terms of boozing.
The students, recruited from the Medical University of Lodz in Poland, were “not alcohol dependent.”