Knowledge: Black coffee is more commonly enjoyed by South Koreans than Italians. On the other hand, brown hair is common among populations in the Western world, especially among those from Europe, the United States, and also some populations in the Greater Middle East.

Conversation:
I have brown hair unlike my sister who is blonde.
Oh, interesting. Were you aware that brown hair is second only to black in commonality?
yes.  it is strange - I wonder where red hair comes from.
I have no idea, but I can tell you that brown hair has more eumelanin and less pheomelanin.
Oh, cool. So where is it common to see this color?

Response: Hmm. Brown hair is more common in the Western World. Mainly in Europe, the US and some areas in the Greater Middle East.