[ This post is a book review of: Gregory Clark (with Neil Cummins, Yu Hao, and Daniel Diaz Vidal and others), 2014. The Son Also Rises: Surnames and the History of Social Mobility. Princeton and Oxford: Princeton University Press. ]

The Son Also Rises forcefully advances the idea that social position is determined by innate inherited abilities, an idea that is potentially pregnant with policy implications. “Once you have selected your mate,” Gregory Clark counsels, “your work is largely done. You can safely neglect your offspring, confident that the innate talents you secured for them will shine through regardless.”

With this book Professor Clark (an economic historian with the University of California at Davis) dons the mantle of Francis Galton, who more than 100 years ago examined the transmission of status across the generations of 19th century England, and who is equally known for the statistical methods he developed to study the issue.

And in the same way that careful readers have both admired and also questioned Galton’s work, so too they can legitimately admire The Son Also Rises as a work of scholarship, while at the same time wonder about it as an exercise in scholastic overreach.

Social scientists have examined many different indicators of the intergenerational transmission of status. Clark draws conclusions from his and his collaborators’ tracking of the status associated with surnames. Galton used height, but earnings and income are particularly salient in recent research, and occupation, education, wealth, and other indices have also figured prominently. The intergenerational transmission of earnings, for example, varies across countries, with the level of economic development, with the degree of inequality, and in some cases over time as policies and institutions change. Other indicators have been found to show less variation across time and space. Whereas much of this research looks back only one, at best two, generations, Professor Clark makes a major contribution in tracing the transmission of status back centuries.

The book holds that previous studies are based on observable manifestations of the intergenerational transmission of a latent characteristic, which earnings, education, occupation and all the other indices measure imperfectly. Clark sometimes refers to this underlying characteristic as “social competence,” and at other times outright as “social genotype,” but ultimately what he means is “genes.” When measured correctly, social competence has a high degree of intergenerational transmission, with about three-quarters of any relative advantage or disadvantage being transmitted from parent to child. This equals or exceeds Galton’s estimate for height, and is as much as three times some estimates of the transmission of earnings between fathers and sons.

But more important, according to Clark social mobility is an unchanging constant. It did not change with the arrival of free public education, the fall of nepotism in both the private and public sectors, economic growth, the expansion of the franchise in the 19th century, or even with the rise of the welfare state and redistributive taxation in the 20th. Social mobility is not related to any of these policies, and it is not tied to the level of inequality.

This, he claims, is a law for all times and all places, from 14th century England, to 20th century China, from the America of the settlers to the America of Wall Street financiers.

I shall call it “Clarke’s law”, my deliberate misspelling of the author’s name paying homage to his use of surnames and changes in surnames, and to the use of the letter e to represent influences other than family background—what Clark refers to as “luck”—in the mathematical representation of a son’s status as a linear function of his father’s status. Clarke’s law states that 50% to 80% of variation in status is predictable at birth. There has always been social mobility, albeit very slow, but it has little to do with society, institutions, or, by implication, public policy.

The book’s first part, an exercise in description, lays out the evidence for this law in countries for which surname information is available for the longest period. The approach involves tracking surnames through time, with due care that spellings may change, and linking them to some measure of social position.

For Sweden, this involves associating uncommon surnames among the Swedish nobility and the educated elite of the 17th and 18th century to the social status of those carrying these same surnames today, as indicated by the names appearing in lists of physicians, attorneys, university students, members of the Royal Academy and even among the high earners in publicly available tax records. The names of titled nobles, for example, appear on the Swedish Bar Association’s register of member attorneys at nearly six times their proportion in the general public, and Clark estimates the persistence of high-status occupations, in general, at about 0.75.

Similar methods are applied for the United States and the United Kingdom, using elite names culled, for example, from the American Medical Association’s directory of physicians, lists of licensed attorneys, or the list of federal tax payers published in The New York Times in 1923-24.

To put these three modern cases in relief, Professor Clark offers surname evidence from Medieval England dating back to 1300. Elite names are identified as people associated with Oxford and Cambridge Universities, with wills proved in the highest court, with those probates associated with “Sir” or “Gentleman,” and with Members of Parliament. The Norman conquerors of England in 1066 recorded as property owners in the Domesday Book of 1086 are 16 times more likely than other names to be represented in Oxford or Cambridge in 1170 and 25% more likely now: a steady, but very slow, regression to the mean, suggesting a persistence rate of 0.90 from one generation to the next. The bottom line is that “medieval England had mobility rates similar to … those of modern United States and Sweden. In terms of social mobility, then, what did the Scientific Revolution, the Enlightenment, and the Industrial Revolution achieve? Very little.” (pages 74 and 75)

This is scholarship at its best, but it also conveys a whiff of overreach that becomes manifest in the second part of the book, which sets out to test the law in diverse countries (India, China, Taiwan, Japan, Korea, and Chile) and also among particular groups (Protestants, Jews, Gypsies, Muslims and Copts).

Claiming that this dynamic applies to society as a whole rather than just to elites, Clark is sensitive to the need for supporting evidence. He repeatedly seeks confirmation that the data are representative of entire populations. Yet at times the analysis is very local—for example, the use of two specific regions in the Shanghai area as the basis for the study of the evolution of status among Chinese surnames.

Even if it is debatable whether or not the various data are representative, it may still be appropriate to claim the law is widely applicable—so long as the proportion of advantage passed between generations does not vary across the social hierarchy (that is, the mobility process is linear). But if Clarke’s law varies with social status, then the book is only about the propagation of elite status across the generations.

The research community examining contemporary patterns in social mobility struggles with both of these issues while using much more extensive and more accurate data than can be imagined for past times. That these issues could be resolved more cleanly by even the best economic history is a suggestion that many may find surprising.

Clarke’s law can be described as a simple regression to the mean model in the spirit of Galton, one in which two components (reflecting the inheritance of genes and the impact of what some might call luck) shape a child’s adult status. But other models can lead to equally high persistence of status. Powerful parents may influence child outcomes directly, rather than through inheritance, as a result of social institutions, and things like primogeniture, nepotism, access to select colleges, or lax wealth and estate taxation. The children of the elite will succeed independent of their innate talents because of this type of social tracking.

Or it may be that the host of other influences on child outcomes should not be thought of as a random draw, as simple luck with no multigenerational echo. A longstanding family culture may foster capacities to, for example, teach children to speak with a socially approved accent, buffer them from the downsides of health risks and other threats to their human capital, or simply to instill an identity of entitlement. A surname is not just an index of genes but also of social pressures and entitlements that keep some down and keep others from falling down. In this way, what Clark terms luck may also persist across generations and it will also generate persistence in “social competence.”

Whether or not Clarke’s law is valid or can be generalized, there is, nonetheless, an important lesson for public policy that should not be lost. Economic development, progressive income redistribution, the rise of public education, improvements in health, and the collective insurance of the welfare state are not inconsequential. The suggestion in this book is that they matter less for relative differences among individuals than we might think or hope, but surely they still matter for the absolute level of well-being and the development of human capacity—a message that may be lost by a focus on relative outcomes.

The author suggests his law implies that earnings and other economic outcomes should not be as unequally distributed as they are in some countries, because they reflect the transmission of genes and therefore competencies beyond individual control. But this is no more than a passing suggestion, and readers will suspect that Clarke’s law will be interpreted just as forcefully in some public policy communities as an argument for the just deserts of those on top of the social heap.

Ultimately, as interesting as The Son Also Rises is as an exercise in historical scholarship, it does not advance contemporary public policy. Galton even began an 1892 book (Hereditary Genius: An Inquiry into its Laws and Consequences) with the same focus as Clark’s beginning and ending of The Son Also Rises: “I propose to show … [Galton wrote on page 1] that a man’s natural abilities are derived by inheritance, under exactly the same limitations as are the form and physical features of the whole organic world. Consequently, … it would be quite practicable to produce a highly-gifted race of men by judicious marriages during several consecutive generations.” We have heard this advice many times over the decades, and it serves neither good public policy nor good parenting.

[This is the author’s version of the book review originally published with the title “Social mobility: fixed forever?” It is posted here by permission of the AAAS (American Association for the Advancement of Science) for personal use, not for redistribution. The definitive version was published in Science Vol 344 (#6186), May 23rd, 2014, DOI: 10.1126/science.1251568 .

I gratefully acknowledge the helpful comments and suggestions of Bruce Bradbury, Andrew Cherlin, and Dalton Conley on a first draft of this post, but remain entirely responsible for the final result.]