According to an unusual study conducted by University of Vermont researchers, people with blue eyes may be more likely to become alcoholics – and researchers are trying to figure out why.

Image via Telegraph.

Human eye color is a pretty strange thing – it’s an inherited trait influenced by more than one gene. These genes cause small changes in the genes themselves and in neighboring genes, and we actually don’t know all the genes responsible for eye color. With ranges from light blue to dark brown, you can tell a lot about a person just by looking at his iris color, perhaps even if he’s more likely to become an alcoholic.

The researchers noticed the link after studying the eye color of 1,263 European Americans who had been diagnosed with alcohol dependence. They found that on average, people with lighter shades of eye color were more likely to become alcoholics than the ones with brown eyes; individuals with blue eyes actually had the highest rates. Even after correcting for variables such as age, gender, and background, the differences still remained.

“This suggests an intriguing possibility – that eye colour can be useful in the clinic for alcohol dependence diagnosis,” one of the lead researchers, Arivis Sulovari, said in a press release.

Of course, the problem here is that correlation doesn’t imply causality – in other words, just because two things happen in common doesn’t mean that one is causing the other – and that’s a major issue. That’s why before jumping to a conclusion, researchers want to replicate the results. But even if they do, it still doesn’t imply causality. For that, they need to find a genetic or environmental cause, and they have a hunch it might be genetic.

However, alcoholism is a complex issue.

“These are complex disorders,” said the other lead researcher Dawei Li. The genes we’ve identified over the past two decades “can only explain a small percentage of the genetics part that has been suggested,” he added, “a large number is still missing, is still unknown.”

But even though causality is not established yet, it may still be an important clue.

“Although replication is needed, our findings suggest that eye pigmentation information may be useful in research on AD,” researchers write in their abstract.

Journal Reference: Eye color: A potential indicator of alcohol dependence risk in European Americans. Arvis Sulovari, Henry R. Kranzler, Lindsay A. Farrer, Joel Gelernter and Dawei Li.