I refer to it as the "Rule of Four." Take a look at most commercials/TV shows/videos that have a group of kids - many times it's four kids and the ethnicity breaks down into two white children (boy and girl), an Asian child, and a black child. For the non-white children, there will be one boy and one girl, but their genders are not tied to the ethnicity. Expect a "Rule of Five" to be the norm in the future - the ever-more-obligatory kid in the wheelchair. It's taking a bit longer for the Hispanic kid characterizations to catch on, but I predict an eventual "Rule of Six."
There was just an ad for some menopause-type drug on TV, with four older ladies in a museum. You guessed it - two whites, an Asian, and a black. In this case, both whites were female but considering the product, that's to be expected.
I find these examples of "mathematical diversity" in TV and film to be incredibly condescending and calculating and an offense to ALL people.
How is at offensive that an advertiser wants their product to appeal to a wide range of people?
I've seen plenty with one white, one black, one Asian and one Hispanic child. I'm sure people look at that and say, "That's fair." But whites make up more than 1/4 of the population! So when a white child actor is up for a role, he has a lot more competition for the same amount of slots. I live in LA and have known people who tried to put their kids in show business. For the white kids, it's always a struggle to get roles, while the minority kids get snapped right up. A black woman I know brings her son to open casting calls and the casting agents fight each other over which one will get to represent him. He's not exceptionally cute or talented, not any more than the white kids I know who go on auditions.
Anyway, not the end of the world, but just one more area where things seem to be a lot easier for nonwhites.