Anyone who has ever had an aquarium of guppies whereby brother and sister guppies are left to mate will find that after months the number of offspring is reduced to zero. In ancient times, before any understanding of biology, farmers noticed that inbreeding diminished fertility and contributed to the morbidity of the offspring. Therefore, an understanding of the downside of incest was well-appreciated by Homo sapiens during the Holocene, which started at 12,000 BCE and which was known for the start of agriculture due to a stable climate and the transition from hunter gatherer societies to city states composed of hundreds of thousands of people (Bowles and Choi 2019; Rockström and Gaffney 2021; Roser 2022).

Securing wealth through monopolies has been more the rule than the exception since the Holocene. Read any spiritual commandments of this period for any part of the world and one will find that there was typically a priestly/noble class that managed and thus was entitled to the wealth, a working class that created the wealth, and a slave class that took care of the wealthy by way of hard labor, entertainment, and procreation (Bankston 2022; Bellwood 1987; Daniels and Bright 1996; Finkelstein and Siberman 2002; Hanson 1995; Hunt 2015; Johnson and Earle 2000; Mallory 1989; Roberts 1996; Schele and Freidel 1990; Stilwell 2013; Van de Mieroop 1997). This class structure has continued to the present but without slavery, which was outlawed constitutionally by the 1950’s throughout much of the world [albeit remnants of slavery still occur in prison populations for which punishment is preferred over rehabilitation].

To hedge their wealth, the following were notorious for using incest as an economic (and power) strategy: Royal endogamy between brothers and sisters was common amongst the Pharaohs of ancient Egypt dated from 2000 BCE (Middleton 1962). King Ptolemy II who ruled the Ptolemaic Kingdom between 284 BCE and 246 BCE married his sister, Arsinoe II, to secure ties with Egypt (Plutarch of Chaeronea 46-120 CE). Incan rulers married their sisters such as Emperor Huayna Capac (1493-1524 CE) with sisters Coya Cusirimay and Araua Ocllo (Cadena 1996; D’Altroy 2014). The Habsburg Dynasty regularly sponsored consanguineous marriage to expand their wealth throughout Europe between 1200 and 1700 CE (Dillion 2018). The royalty of Hawaii in 1700-1800 CE was well known for having incestuous relations between family members (Carando 2002). Finally, the Rothschild Banking Dynasty (1567-1879 CE) used incest to secure its wealth by marriage between cousins (Kuper 2001).

Although in recent time examples of incest to secure one’s economic wealth is less common, this does not mean that a plutocrat’s desire to hold on to wealth is any less today than it was in the past. Given the availability of new genetics vis-à-vis paid surrogates, a billionaire can hoard wealth by taking an ‘asexual’ approach to inheritance, whereby their offspring do not need to split their wealth with maternal or paternal relatives. This is exactly what Elon Musk has done to keep his money within his family. Elon’s last child was conceived using IVF (in vitro fertilization) and surrogacy (Zhavoronkov 2022). This approach does not have the genetic shortcomings of incest.

As stated by Zhavoronkov (2022): “One of my friends decided to reproduce via a surrogate to have undisputed legal rights to ensure that his plans to invest substantial resources into the upbringing and education of their offspring do not go down in flames due to the unexpected divorce.”—and due to the unexpected diminution of asset value because of the divorce.