Can drinking alcohol as early as 7 or 8 years old once per week stunt your growth? especially your height growth?

Not sure: what exactly you mean by "alcohol once a week". First of all no 7 or 8 y/o should be consuming alcoholic beverages. I am not sure that it is the alcohol per se though that is the only factor if your growth was stunted. Many other factors including genetics, diet, stress etc. But not a good idea for preteens to be consuming alcoholic beverages

Unknown: There are some cultures that offer wine or beer in limited amounts to children in various settings.They have done so for generations and the kids survive. However, these tend to be minor exposures over time. We know that alcohol is toxic to developing brain cells at any dose, and have no way to examine the effect of these minor exposures on height/growth.