What is the origin of the idiom "fair-haired boy" and when to use it?

The origin of the idiom "fair-haired boy" can be traced back to ancient folklore and mythology. In many cultures, fair or light-colored hair was associated with beauty, purity, and innocence. The phrase gained prominence in English literature and language during the 19th century. It is often used in professional or organizational settings to refer to individuals who are seen as exceptionally talented, promising, or successful.