Most home made soft drink makers use yeast to carbonate the drink. Sugar is needed to cause the yeast to create the necessary CO2. This will also cause a small amount of alcohol to be produced.

"A WORD ABOUT THE ALCOHOL IN HOME MADE ROOT BEER (OR GINGER ALE ): I have received numerous inquiries about whether there might be alcohol in this home made soft drink. The answer is yes, but... We have tested in our lab the alcoholic content which results from the fermentation of this root beer and found it to be between 0.35 and 0.5 %. Comparing this to the 6% in many beers, it would require a person to drink about a gallon and a half of this root beer to be equivalent to one 12 ounce beer."

Here are the instruction for root beer with a liquid extract.
http://biology.clc.uc.ed.../cheese/rootbeer_jn0.htm


Root beer is naturally caffene free