The alcohol content in home-made ginger beer depends on various factors such as sugar, temperature and fermentation time. Depending on this, you can get a content of between 1-5% in your ginger beer. You usually can't achieve a higher alcohol content with a wild yeast starter like Ginger Bug.
If you want to produce as little alcohol as possible, don't let your ginger beer ferment for more than 3-5 days and store it in the fridge from then on. If you consume your ginger beer soon, the alcohol content will remain very low. We recommend tasting the ginger beer briefly before offering it to children, for example.