Where characters with fair hair can be seen more frequently than expected for what should be a melting pot population. Specifically, you can see a disproportionate number of blondes for the setting when a show has no fewer than half of the female Caucasian cast being blonde. It can include the whole Caucasian cast. Similar to Blonde, Brunette, Redhead, but on the other end of the scale. The thing is that film casters believe the audience finds blond hair to be beautiful, so if you want to be a movie star, it helps to look good with fair hair. Usually, it's a white-yellow shade but sometimes darker. They can range from identical twins to a bunch unrelated characters.