Human DNA is about 99.5% identical from person to person. However, there are small differences that make each person unique. These differences are called variants. The company 23andMe can provide information relating to your health and ancestry by testing your saliva, such as whether you flush red in the face after drinking a small amount of alcohol, i.e. an alcohol flush reaction.
Apparently, people who experience flushing may also experience unpleasant symptoms like headaches, nausea, and sleepiness. My own result was as follows:
This means that whilst I am unlikely to begin flushing bright red after having one drink or less, I could still experience unpleasant symptoms like flushing if I was to drink too much in a short amount of time. That is because alcohol is broken down into a toxic substance that may build up faster than it can be cleared out. As we all know, avoiding heavy alcohol consumption is important for overall health.
According to 23andMe, before alcohol molecules can be cleared from the body, they have to be broken down into smaller molecules. Acetaldehyde is one of the molecules created during this process. For people who don’t have the alcohol flush reaction, acetaldehyde is quickly broken down further into another, harmless substance. But for people who have one or two copies of the alcohol flush variant, the enzyme responsible for breaking down acetaldehyde is less efficient, so acetaldehyde builds up in the body faster than it can be cleared away.
Another interesting aspect is that this reaction to alcohol is linked to human migration, with a disproportionate predominance found in East Asia.
As always, your genetic make-up is only partially responsible for the outcome and there are other factors that affect the alcohol flush reaction, as outlined below. On a final note, if you are interested in your own ancestry and health relating to your genes, I would recommend 23andMe and its test.