Wine is a simple beverage, primarily composed of the juice from grapes; the alcohol comes from the sugars in those grapes. Basically, that’s it. Sure, yeast is added to create the fermentation (something Louis Pasteur discovered in 1857), but it’s removed before you buy a bottle. And yes, some wines are aged in oak barrels to give the wine maturity or flavor. But for the most part, wine’s flavors come from the grapes that are used to make it. A gewurztraminer will be spicier than a pinot gris, which may be a bit spicier than a sauvignon glanc, which is a bit grassier or more lemony than a chardonnay.