Although you would have to read the Washington Post story carefully to know it, social mobility in America is alive and well.
The Post story, by Annie Gowen, tells us gloomily that 43% of those who are born into lower class families stay in the lower class, and that 40% of upper class children remain in the upper class.
Another way of looking at that is that a majority — 57% — of lower class children rise to at least middle class status. An even larger majority — 60% — of the wealthy will not remain wealthy, proving that merely inheriting money is no guarantee against dropping into the middle class or lower.
The liberal argument that the Death Tax is needed to prevent the wealthy from making their descendents a permanently wealthy dynasty turns out to be groundless.