Social mobility myths
Those who recommend social mobility tend to focus on upward movements. John was born into a bottom-income quartile family, but now he is in the top quartile. Good for John. Alas, every upward social movement requires an equal quantity of downward movement. Just as a tennis player cannot climb the world rankings without others falling, so John’s ascent in the social rankings guarantees that others descend. And their losses must be exactly equal to John’s gain. When everyone is taken into account, it is simply impossible for social mobility to deliver a net benefit.
He also points out that:
In modern economies, the intelligent and well-educated tend to have higher incomes. Intelligence and educational performance are largely inherited, through both nature and nurture. People tend to marry within their own social class. If these tendencies are very strong, then we should expect almost no social mobility in a meritocracy. Those with the attributes that get them to the top (merit, let’s call it) will produce children with merit, who will also get to the top and produce children with merit . . . and so on for generation after generation.Indeed, this was largely the point made by Charles Murray and Richard Hernstein in their book The Bell Curve, although much of it was lost in the accusations of racism when the book came out.
Anyway, have a look at Whyte's article.