One in six U.S. adults binge-drinks four times a month, consuming an average of eight drinks per session, according to the Centers for Disease Control and Prevention -- and binge drinking is practically a rite of passage on college campuses nationwide. But why do some people feel so compelled to throw back a few drinks while others have no interest at all?

Blame it on the genes.

According to a new study published in the Proceedings of the National Academy of Sciences, researchers have found a gene that plays a starring role in how alcohol stimulates the brain to release dopamine, triggering feelings of happiness and reward.

"If people have a genetic variation of the RASGRF-2 gene, alcohol gives them a stronger sense of reward, making them more likely to be heavy drinkers," said Gunter Schumann, who led the study at King's College London's Institute of Psychiatry.

In the study, scientists examined brain scans of 663 14-year-old boys and discovered that when they were expecting a reward for a mental task, those with genetic variations to the RASGRF-2 gene had more activity in the area of the brain that activates dopamine release. The researchers concluded that people with the genetic variation release more dopamine when anticipating a reward, then derive more pleasure from it.

Two years later, the scientists examined the drinking patterns of the same boys and found that those with the gene variation drank more often than those without it. This isn't proof that the gene causes binge drinking, but the findings help shed light on why some people appear to be vulnerable to the allure of alcohol.

"This appears to be one gene that regulates how rewarding alcohol is for some people," said Schumann. "People seek out situations which ... make them happy, so if your brain is wired to find alcohol rewarding, you will seek it out."