Measuring inbreeding allows study to isolate rulers from circumstances
A piece of century-old research that sought to identify which European monarchs, between the years 1000 and 1800, were effective leaders — and which ones botched the job — left some unfinished business.
Did the rulers deemed by that study to be successes merely have the wind at their back — and the failures a run of bad luck — or was there actually something about the individuals that caused them to perform as they did?
In search of a set of data that would suggest causation, not merely correlation, UCLA Anderson’s Sebastian Ottinger, a Ph.D. student, and Nico Voigtländer, using Roglo, a genealogical database, collected a “coefficient of inbreeding” that measured the degree of genetic similarity for more than 250 monarchs. By tracing parentage over centuries, they were able to determine the degree of hidden genetic connections that built up over generations of intermarriage.
Not every leader was heavily inbred — even those in a family where intermarriage was prevalent. It’s as if less able, or more able, leaders were randomly introduced across the Continent and centuries. By identifying degrees of inbreeding, researchers were able to separate ability from circumstance — the forces beyond a leader’s control that either propel a country upward or to ruin. Deciding whether leaders are effective or whether they merely happen to come to power during good times — be they heads of state or corporate chiefs — remains a troubling question today.
The working paper, published by the National Bureau of Economic Research, suggests indeed that a higher concentration of inbreeding in a monarch led to worse outcomes for his or her country. And combining that with additional assessments of ability, the authors conclude that leaders influenced the performance of their state.
Charles II, king of Spain from 1665 to 1700, for instance, was the son of a niece-uncle marriage. His parents were also the products of generations of marriages between the Spanish and Austrian Habsburgs, such that Charles II’s parents shared as many genes as siblings would.
Charles II became king at age 4 and suffered physical and mental disabilities. His head was large and misshapen, and he had a Habsburg jaw so prominent his teeth could not meet to chew. Charles II didn’t talk until age 4 or walk until age 8 and couldn’t read or write. Consequently, he was widely described as an ineffective monarch and incapable leader, and Spain suffered greatly under his rule, as reflected by poverty, agricultural production and the strength of its armed forces. Charles II had no children and was the end of the Spanish Habsburg line.
In 1759, a man from an entirely different family, Charles III, came to power in Spain. His parents were cousins of the third degree, which meant the level of inbreeding was substantially less than that of Charles II. Under the direction of Charles III, Spain’s economy thrived, and he was hailed as one of the most influential monarchs of his generation.
The impact of inbreeding on the Spanish Habsburgs is a well-told story. But Ottinger and Voigtländer, by quantifying intermarriage across the centuries and nations of Europe, show inbreeding’s impact more broadly and definitively.
Today, it is widely accepted that consanguineous parenting, defined as a union between individuals who are second cousins or closer, poses a genetic threat, including heightened risk of impaired mental ability and diseases such as cystic fibrosis and Down syndrome. But for most of history, inbreeding wasn’t frowned upon and in fact was favored.
The century-old study Ottinger and Voigtländer seek to build upon — actually, to refute in part — was authored by a proponent of intermarriage, in fact.
Frederick Adams Woods was a Harvard-trained physician and instructor at MIT. And according to his 1939 New York Times obituary, Woods was the chairman of the American Genetics Association’s committee on research in eugenics between 1914 and 1923. In a 1914 Scientific American article he authored, he opined, “broadly speaking, all our very capable men of the present day have been engendered from the Anglo-Saxon element.” He lauded “the natural tendency of the most successful to mate among themselves.”
Clearly, if Woods were alive today and expressing those beliefs, he’d be labeled a racist and a crank. Woods thought moral and intellectual ability was inheritable and that kin marriage among successful dynasties would produce better rulers. His 1913 book, “The Influence of Monarchs,” assessed the efficacy of more than 300 monarchs from 13 European states. He based that analyses on assessments found in biographies and other historical documents, and is said to have coined the term historiometry, a sort of data-sourced approach to the Great Men Theory.
Ottinger and Voigtländer employ Woods’ assessment of monarchs, and they find the exact opposite of what Woods theorized: that inbreeding was a disaster for ruling families and their nations.
In their paper, they note that “Woods assigned a “+” to able rulers, a “-” to incapable ones and “±” to those not clearly capable or incapable. E.L. Thorndike of Columbia University, another proponent of eugenics, had a team in 1936 essentially re-check Woods’ work, ranking the rulers from 1 to 10. Those findings were in agreement. Ottinger and Voigtländer also had a research assistant assess the capability of individual rulers on the three-point scale of Woods (1913) using articles in online encyclopedias. “This exercise also largely confirmed Woods’ coding,” the authors report.
Expanding on the assessments, Ottinger and Voigtländer also tracked the size of territory during each ruler’s reign. More capable leaders tended to expand their territory. Of the 331 monarchs about which they were able to gather information on ability and performance of country, 124 were rated clearly incapable, 120 clearly capable and 87 as neither.
Europe’s citizens were not completely at the mercy of their ruler’s genetics, according to this research. It suggests countries that adopted institutional constraints — such as the parliamentary form of government — saw a lessening in the relationship between ruler ability and state performance. This may have helped shield “Northern Europe’s states from the adverse effects of inbreeding within their ruling dynasties,” the authors wrote.
About the Research
Ottinger, S. & Voigtländer, N. (2020). History’s Masters: The Effect of European Monarchs on State Performance.