Most people intuit that coming from the “right sort” of family is a big advantage in life, while being from the “wrong side of the tracks” is a serious disability. And they suspect that these advantages and disadvantages persist, as demonstrated by the continuing prominence of, say, people whose ancestors “came over on the Mayflower” among the upper crust in America.

The difficulty with this intuitive understanding is that social-science research does not seem to back it up. Psychologists, sociologists, and economists have found rates of social mobility that ought to wipe out all familial advantage or disadvantage within three to five generations. Furthermore, the rates of social mobility found in most of these studies differed greatly from one country to another, with, for instance, Sweden scoring much higher than the United States in this regard.

So is this belief in the persistence of familial advantage just a popular delusion? That is the question that U.C. Davis economist Gregory Clark takes up in his new book, and the answer he found surprised even him. He set out thinking the social-science consensus was correct, intending only to extend those findings further into the past. But the evidence changed his mind: social scientists have been measuring mobility the wrong way, and in fact the popular intuition is on target.

The key to understanding Clark’s thesis is his division of the factors that make for success in worldly affairs into an inherited component and a random component. (“Inherited” here need not mean “genetic”: one could inherit, for instance, one’s family’s reputation.) Most previous studies have focused on movements in social class from one generation to the next. But as Clark explains using his two-factor model, such a limited time frame means that the random component of social achievement is going to have an undue influence. This is not an esoteric notion: think, for instance, of a member of a high-achievement family who suffers a terrible car accident as a youth, leaving him with severe brain damage. It is quite likely that whether measured by income, profession, or educational level, that member will do significantly worse than the family average.

But this accident will not change the family’s basic “social competency” (Clark’s term). If the injured son has children, they will not inherit his brain damage. Their level of achievement will tend to return toward the family baseline. So, Clark suggests, if we really want to measure social mobility, we should look at the social status of families over many generations.

The way he and his team of researchers did so is ingenious: they found relatively rare surnames primarily associated with high social standing, such as the names taken by the nobility in Sweden, or low social standing, such as names characteristic of the Travellers in England, and tracked their appearance in historical records showing elite status, such as admissions to top universities—for Oxford and Cambridge, we have data dating back 800 years—large estates bequeathed in probate, or presence in high-status professions such as law and medicine.

The results confirm that the popular intuition has been correct all along:

The intergenerational correlation in all the societies for which we construct surname estimates—medieval England, modern England, the United States, India, Japan, Korea, China, Taiwan, Chile, and even egalitarian Sweden—is … much higher than conventionally estimated. Social status is inherited as strongly as any biological trait, such as height.

What’s more, it matters little what social policies are put in place: Clark and his team find that social mobility remains nearly constant over time despite the arrival of free public education, the reduction of nepotism in government, modern economic growth, the expansion of the franchise, and redistributive taxation.

Clark introduces us to the reality of this persistence of status with a few notable examples. For instance, the family of famed diarist Samuel Pepys has had high social status from 1500 until today, while that of Sir Timothy Berners-Lee, creator of the World Wide Web, apparently has been upper crust since the Domesday Book of 1086. And in noting the many prominent members of the Darwin family, he remarks, “It is also interesting that Darwin’s fourth-generation descendants include Adrian Maynard Keynes and William Huxley Darwin.” The elite tend to marry the elite.

But if such isolated examples were the crux of Clark’s case, it would be a rather flimsy one: even if the standard social science take on mobility were correct, we would expect to find notable exceptions to the general rule. His main backing for his thesis is a number of studies conducted across many countries and many centuries. Nevertheless the anecdotes are an important aspect of this work: they are a component of how Clark continually turns what could have been an extremely dry executive summary of a number of demographic surveys into a consistently engaging book.

While I am no expert on the literature concerning social mobility, it seems to me that Clark has backed his thesis with very significant and relevant data. But I would want to see responses from those defending the more traditional social-science view on social mobility before unconditionally awarding the victory to Clark.

One way in which Clark gauges the social status of an ethnic group is to see how the proportion of doctors in the group compares to the proportion in the population as a whole. This measure is not flawless: in the case of Filipinos, I think it must overstate their status, as they seem to be a people that just love the medical professions. (Having married a Filipina, I have found that roughly 80 percent of my in-laws are doctors or nurses.) But it is a good rough gauge nonetheless. Clark uses this gauge to evaluate the elite status of various ethnic groups by looking at the surnames of registered physicians in America. Which ethnicities top the charts of U.S. doctors?

Here they are, starting with a group that produces physicians at 13 times the national average: 1) Coptic Egyptians, 2) Indian Hindus (about 12 times the average), 3) Indian Christians, 4) Iranian Muslims, 5) Lebanese Christians, 6) Ashkenazi Jews, 7) Sephardic Jews, 8) Koreans, 9) Chinese, 10) Filipinos, 11) black Africans (we’ve reached about four times the average here), 12) Greeks, 13) Armenians, 14) Japanese, 15) Vietnamese, 16) black Haitians.

So, what do we find among the top 16 doctor-producing groups in the United States? No European Protestant group. This calls into question the notion of “white privilege”: being a physician is a high-income, high-status profession. If white privilege is a significant social force, why doesn’t a single European-Protestant ethnicity appear among this top 16? Why do our populations of black Africans and black Haitians produce doctors at significantly higher rates than Dutch-Americans, Swedish-Americans, or Finnish-Americans, all groups that make up a low enough percentage of our population that they cannot be said to constitute the average merely by their numerical preponderance? Clark does not try to deny that many white Americans harbor prejudice against non-whites. But this prejudice, however real, apparently is not preventing many non-white ethnic groups from achieving high social status.

And if white privilege is really a major force in the United States, what are we to make of the persistently low social status of French Canadian immigrants, a group of people that is, after all, pretty darned white, and many of whom have been in the States for a couple of centuries? (I had no idea this low social status was even the case before reading Clark’s book. Did you?) Clark explains this fact as being due to a double-selection for low social achievement: the initial population of French Canada came primarily from the lower-status population of France, and then it was chiefly lower-status Québecois who emigrated to America. Americans of French Canadian descent are in fact reverting to the mean and becoming more like the rest of our population; but starting from a very low initial position, they are doing so slowly, just as Clark’s model predicts.

Clark discusses several apparent exceptions to his “law of social mobility.” He finds they all fall into one of two categories. A group with exceptionally lengthy high or low social status may persist in that status because members do not intermarry with other groups, such as the Brahmins in India. Or the group in question may experience selective in- and out-migration, such as the Travellers in England—whom Clark argues are not ethnically distinct from the general population—so that lower-status people who want a migrant lifestyle joined the Travellers, while those wishing to move up in status left the group.

A flaw in this book is Clark’s tendency to treat the abstract model he has developed to capture his findings as if it were an actual causal agent operating in the real world. Consider the following passage:

If a group deviates in the current generation from the mean social status, set at zero, then on average will have deviated by a smaller amount, determined by b, in the previous generation. A group of families now of high social status have arrived at the status over many generations by a series of upward steps from the mean. And the length and speed of that ascent, paradoxically, are determined by the rate of persistence, b.

This is a perfect example of what Alfred North Whitehead referred to as “the fallacy of misplaced concreteness.” In reality, what we have are particular, concrete individuals, members of families, doing this and that in the world and succeeding or failing to some degree or another. From a large number of such individuals, Clark has devised a model of changes in social status. Within that model, there is a parameter, which he calls b, that is determined by the average speed of ascent or descent in social status among family members.

It is these actual, concrete activities that make b what it is. But Clark gets this exactly backwards: for him, this abstract entity, b, is somehow controlling the actions of real-world individuals. It is like thinking that a baseball player’s batting average determines how often he will get hits, as if somehow a number on the TV screen can influence his swings, rather than how often he gets hits determining his batting average.

Enough with the details: what is the general upshot of Clark’s findings? For one thing, even if we believe that social mobility ought to be as high as possible, his data do not support the idea that we ought to undertake major social engineering projects with the goal of increasing it. If public education, a universal adult franchise, redistributive taxation, or even the radical egalitarianism of Mao’s China did not alter social mobility in any significant way, just what would we have to do to dramatically change it?

We might have to adopt the sort of dystopian measures that Kurt Vonnegut contemplated in his short story “Harrison Bergeron,” where people who are too intelligent are subjected to deafening noises that continually interrupt their thoughts. If that sort of thing is the only fix available, then perhaps we ought to accept social mobility for what it is and welcome the contributions to social life made by the more adept without seeking to cripple them with equal-outcome producing handicaps.

Clark notes that his findings do not indicate that we will have perpetual upper and lower classes: although social mobility for families is slower than others had estimated, it is real, and it means that over the centuries no particular clan will remain on top or at the bottom. In the meantime, Clark suggests a broad adoption of a Scandinavian-type social-welfare model: after all, if social status is largely a matter of being born into the right or wrong family, why shouldn’t public policy act to balance out such an effect of mere luck? Whether Clark is correct in drawing such a conclusion from his data, I leave it to my reader to decide. But if such issues concern you, you should read this important book.

Gene Callahan teaches economics at SUNY Purchase and is the author of Oakeshott on Rome and America.