Is the Connection Between Blue Eyes and Alcoholism a Myth?

The Link Between Blue Eyes and Alcoholism: Myth or Fact?

The root cause of alcoholism, or alcohol use disorder, is a mix of our unique biology, personal history, personality tendencies, and environment. It’s a whole coop of metaphorical chickens and eggs, without a clear way to tell which came first.

However, with the rise of genetic studies, there’s been lots of speculation about what traits may or may not be connected to alcohol use disorder (AUD). One claim? The supposed connection between blue eyes and AUD (and, more specifically, the link to higher alcohol tolerance).

While we can safely say that blue eyes don’t promise AUD in the future, could there be something to this connection? Do people with blue eyes have a higher alcohol tolerance? And are blue eyes, alcoholism, and tolerance somehow linked? Let’s explore!

The Genetics of Eye Color

To start,  let’s take a brief look at what gives rise to eye color in the first place. It comes down to our DNA — the sequence of nucleotide molecules that work as templates for building our body’s proteins. Each stretch of three nucleotides corresponds to amino acids — the molecular building blocks of proteins. Other specialized mechanisms in our cells string these amino acids together according to the DNA template with each “gene” (a sequence of DNA) corresponding to a single protein.

In the case of eye color, the protein in question is located on the OCA2 gene, which codes for a protein that controls the production of melanin — a pigment responsible for dark eye color. Our irises contain organelles called melanosomes, which contain melanin. The more melanosomes (and melanin) we have, the darker our eyes look.

In the most general sense, geneticists consider dark eye color to be a dominant trait and light eye color to be recessive. Recessive traits show up if the offspring receives two copies from each parent, but in the case of a dominant-recessive combo, the dominant trait wins out. 

For example, let’s take the flower color of peas — an example used by Gregor Mendel, who first described heritable traits. Purple is dominant, while white is recessive. As a result, a flower with two purple alleles (or with one purple and one white allele) will end up with purple flowers. The only way to get white flowers? Two copies of the white allele — an outcome that will be a lot more rare.

But wait a second, what about that brown-eyed kid your blue-eyed friend had with her blue-eyed husband? Before anyone rushes to any judgments (or calls Dr. Phil to ask for a paternity test), rest assured this doesn’t suggest anything untoward. As a Nature article on the genetics of eye color points out, there’s more than meets the eye here (pun intended). Additional genes play a role as well, making eye color a complex trait. As the authors of the article explain, there are many intermediate color possibilities — for example, green, hazel, and even albino eyes that lack pigment entirely — and many additional “major” and “minor” genes play a role in the process of giving our eyes their unique color.

Understanding AUD

What we do know, however, is that alcohol misuse has to do with the concepts of tolerance and dependence. While tolerance doesn’t always lead to dependence, the two are connected, and an increased ability to tolerate alcohol can lead to greater intake (possibly to the levels of misuse) and, eventually, a physical reliance (dependence) on the substance.

The mechanism behind tolerance and dependence is based on the way alcohol affects our brain — most notably the way it changes the balance of neurotransmitters in the brain. Drinking causes a brief boost in dopamine, the feel-good neurotransmitter that fuels the brain’s reward circuit. It also increases the levels of GABA (a neurological sedative) while down-regulating its counterpart, glutamate (an excitatory neurotransmitter). The result? A brief euphoric boost followed by sedation.

• Tolerance sets in when our brain and body get used to the presence of alcohol — basically, we start needing more to get the same effects.
• Misuse happens when drinking starts to interfere with our life. How much is “too much”? According to the National Institute on Alcohol Abuse and Alcoholism, heavy drinking is defined as 4 or more drinks per day (or 8 or more per week) for women and 5 or more daily drinks (or 15+ per week) for men.
• Dependence develops as the brain and body adjust to the new normal and come to expect the usual dose of alcohol. If alcohol is suddenly removed, we experience negative effects — the notorious withdrawal symptoms, which include nausea, elevated heart rate, and, in severe cases, seizures and delirium tremens (DTs).

The Genetics of AUD

When it comes to what causes AUD, the genetics behind it are even more complex than those of eye color. In general, scientists agree that there are genetic and environmental factors at play, with many variables that make pinpointing an exact “cause” nearly impossible.

That said, there’s a definite genetic side to AUD. There are two major genes associated with it: ADH1B and ALDH2. Both have to do with alcohol metabolism — a process that happens in the liver and involves two main steps. The liver first breaks down ethanol into acetaldehyde — a compound that’s even more toxic than alcohol itself. The next step is breaking down acetaldehyde into harmless acetic acid, which is then ushered out of the body via the kidneys.

How do ADH1B and ALDH2 fit into the picture of alcohol tolerance, misuse, and dependence? Here’s the gist:

• The ADH1B gene codes for the enzyme involved in the first stage of alcohol metabolism. Variations in this gene can turn the dial up, making the body break down alcohol faster, or turn it down, leading to a slower processing speed.
  
  People with mutations in the ADH1B gene tend to break down alcohol so quickly that it causes unpleasant effects, such as facial flushing and nausea. As a result, they might naturally tend to drink less. On the other hand, those who break it down more slowly might be inclined to drink more — a tendency that could set them on the fast track to developing a higher tolerance and dependence and increase the chances of alcohol misuse.
• The ALDH2 gene acts as the blueprint for the enzyme that takes over the second stage of alcohol metabolism, which involves breaking down toxic acetaldehyde into nontoxic acetic acid. Having a variation in the ALDH2 gene throws a wrench in this process, causing acetaldehyde to build up. 
  
  The result? The mother-of-all hangovers, even from small amounts of booze. Just as in the case of ADH1B variants, this mutation can be a natural deterrent that makes people think twice about drinking, especially in large amounts. 

In addition to affecting alcohol metabolism, our genes might play a role in the actions of neurotransmitters involved in AUD — in particular, GABA. Some studies have suggested that variants in GABA receptors (proteins involved in neurotransmitter signaling) might make some folks more susceptible to the effects of booze. However, although this mechanism functions more clearly in other disorders (such as epilepsy), its role in AUD isn’t as clear-cut.

Investigating the Connection: Booze and Blue Eyes

So what does any of this have to do with blue eyes? As far as actual genetic evidence is concerned, the connection is unclear. There is no official link between the genes involved in eye color and those responsible for the glitches in alcohol metabolism.

So is it all a myth then? Not quite. Although the link hasn’t been confirmed through genetic studies, it has been suggested in some observational studies, which point to a possible genetic connection that hasn’t been found yet.

A review article in Missouri Medicine titled “More than Meets the Eye: Eye Color and Alcoholism” focuses on research studies conducted on the subject. Here are the main takeaways:

• One recent study in the American Journal of Medical Genetics found a link. The researchers looked at 1,263 European Americans who fell into two groups: some were diagnosed with AUD, while others simply had a habit of indulging in a few drinks now and then. As it turned out, the first group did have more blue-eyed folks than the second, which included more brown-eyed participants. The findings left the researchers with the surprising conclusion that the “correlation [between eye color and alcoholism] was markedly higher for blue eyes.”
• Another study published in Personality and Individual Differences found a link as well. In this case, a team of researchers looked at archival data samples of 10,860 Caucasian adult male inmates in the Georgia state prison system. As it turned out, 42% of blue-eyed prisoners struggled with booze, while only 38% of their dark-eyed counterparts did. The same was true for the 1,862 Caucasian American women in the same prison system as well!

As for the connection between blue eyes, alcohol tolerance, and the greater possibility of dependence as a result, there’s some research backing this theory up as well. In 2000, a group from Georgia State University found that melanin might increase the intensity of alcohol’s effects, making brown-eyed people feel it faster. Why? There are two possibilities:

• Melanin may speed up the transmission of alcohol-induced signals to the brain. 
• On the other hand, the reason might have to do with the endocrine system responding differently to light waves that pass (or don’t pass) through our eyes, depending on the presence or absence of melanin.

Looking Beyond the Blue 

After reading these studies and looking at your own blue eyes in the mirror — or into the blue eyes of someone you care about — it can be easy to panic. But don’t! It’s important to know how to interpret these types of findings.

For one thing, correlation doesn’t necessarily mean causation. It’s true that scientists see a link and have a few theories about the biological mechanism behind it. Still, that’s all it is — a possible link.

Plus, when we’re talking about a complex issue such as AUD, there are many additional factors at play. Sure, there’s a genetic predisposition, and blue eyes might be one sign that something in our genes makes us a bit more likely to respond to alcohol differently, but that’s where it ends. 

Many factors predispose us to alcohol misuse, even gender, but predispositions don’t make our choices for us. It makes sense to be aware of the risks, but other than that, we get to determine what role alcohol plays in our lives.

Tips for the Journey

Ultimately, what “causes” AUD is the way we drink. And, if we’re vigilant about it and spot our patterns early on, we can get back in the driver’s seat and take charge of our trajectory.

No matter what your eye color is, here’s what you can do to stay safe:

• Watch your intake. If you choose to drink, make sure you take it slow. Alternate with water and take nights off!
• Track your patterns. If you’re trying to cut back or quit, start by noticing your patterns. Don’t judge yourself — you’re simply gathering information so you have the full picture of your habits. Awareness sheds light on habits we fall into automatically and can make all the difference.
• Expand your options. There are so many booze-free activities to try out there! Try ones that help boost dopamine naturally, such as creative pursuits (think art, making videos, writing blogs, or recording podcasts — even if it’s just for you and a close circle of friends).
• Get sober-curious. There’s a growing sober-curious movement that’s gaining traction around the world! Check out the sober events (concerts, non-alcoholic beverage tastings, gallery openings, or picnics) in your area.
• Find your tribe. Getting a new habit to stick is that much easier if you have like-minded folks around you. The Reframe community (including our 24/7 Forum with Reframers around the globe sharing their stories and support) is here to support you and cheer you on along the way!

Key Takeaways

All in all, AUD is a complex condition that involves genetic and environmental factors alike. Do blue eyes have a higher alcohol tolerance correlation, and is there a connection between blue eyes, alcohol dependence, and AUD? Possibly — but even if so, it’s only one out of the myriad components, many of which are entirely up to us. So whatever your eye color happens to be, enjoy your unique look and know that the future is entirely in your hands.