An article from U.S. News talks about how scientists have discovered that people who like black coffee likely inherited this preference from someone in their family. Scientists found that black coffee drinkers' have a genetic variation that allow them to metabolize caffeine much faster than a regular person. Because they metabolize caffeine faster, the stimulating effect that caffeine has wears off much faster as well, and this results in them drinking more or stronger coffee. Scientists believe that these people begin to association the bitter taste of coffee with mental alertness and the stimulation caffeine gives them, and they tend to have a preference for other bitter foods like dark chocolate.
As someone who does not particularly like coffee or drink it, I find this very interesting especially since I could never understand why some people find black coffee so appealing. It is amazing to learn that a genetic variation that changes the way someone metabolizes caffeine can create this learned behavior and preference for bitter tasting foods.