Thanks a lot for sharing your stories and many interesting articles, just thought of sharing mine too.
I am from southern Europe and in my late 20s and no Asian descendants that we are aware of. I have been drinking since 14/15 I guess but the last 2 years I have been cutting down a lot until I finally decided to quit completely before the summer. As many of you, I also get a very red face while drinking but these last two years have also brought headaches while drinking (not the day after) and very bad stomach pain and in few occasions also led to diarrhea. I should also add that I did get tipsy in many occasions but probably only couple of times actually drunk, although the quantity of ingested alcohol have been quite important. So I decided to get checked for allergies and my general practitioner said that the results showed intolerance to alcohol but I never investigated further and just accepted the fact that I should not be drinking, not difficult given all the negative effects I was experiencing. Until today when I happened to speak with a friend from Scandinavia who has the same symptoms, also in her late 20s and developed it in recent years.
I will get checked again now that I feel like I know a bit more on the matter and will share the response. In the meantime thank you again for sharing