The Maker's Mark Mystery

The question was, "Why does Maker's Mark taste so sweet?"

I found a satisfyingly meaty answer:

Maker’s distinguishing feature is the use of wheat, making it a “wheated” bourbon. One of the requirements of bourbon is that it must be made of at least 51% corn, but some amount of rye is also usually used. Maker’s Mark cuts back on the rye and uses wheat, which creates and milder, sweeter whisky. from Drink Dogma here

The variation in bourbon production results from several sources including length of barreling, barrel and storage conditions, type of water used in cutting the bourbon, and distillation processes and amounts, but the most influential and basic difference among bourbons results from the other 49%. Woodford uses only 18% rye and adds 10% barley, cutting back on the spicy elements of the rye. The result is a bourbon that is milder and sweeter. While relatively few bourbons utilize the wheated approach, the popularity of those that do have surged over the past few decades. Makers Mark pioneered this approach with little success until recently; recognizing this growth in demand for a sweeter bourbon, Brown Foreman began producing Woodford Reserve. Other examples of wheated bourbons include W.L. Weller, some Pappy Van Winkles, and Old Fitzgerald. While not a wheated bourbon, Woodford Reserve is clearly appealing to this market. from Drink Dogma here