Long before the concept of "designer babies" created in a lab became the stuff of science fiction, inbreeding in royal families was viewed as a way to ensure genetic purity. Intermarriage ensured that no "common" blood sullied pure, aristocratic bloodlines. Inbred royalty - what could go wrong?
A lot, actually. Birth defects caused by inbreeding were rampant in royal families from Russia to Portugal and even in ancient Egypt, where the practice of sibling marriage was considered godly behavior. Royal family hereditary diseases and deformities caused by inbreeding - such as porphyria, among others - get handed down through thin gene pools, particularly in the many cases where intentional close marriage is used to ensure that royal blood (and its recurrent flaws) are kept in the family. For example, Queen Victoria, a major proponent of pure bloodlines, married her cousin Albert, and the two had nine children who then passed hemophilia to royal families throughout Europe.
While all these families hoped close intermarriage would keep their royal families stronger, in many cases, illness, madness, infertility and deformities caused by inbreeding ended up tearing them apart.
Ferdinand I Of Austria Had A Host Of Mental And Physical Problems, Yet Reigned For 13 Years
Emperor Franz II of Austria married his double first cousin Marie-Therese, but their son paid the price for the proximity of their blood. Ferdinand I was born in 1793 with a hydrocephalic head containing fluid build-up and pressure that severely challenged his intelligence and motor skills. He also had the Habsburg jaw and a tongue far too large for his overbite, a body too small for his head, and epilepsy.
Still, he ruled from 1835 to 1848.
While Cleopatra is known in popular culture for her slender figure and stunning beauty, it's more likely she wasn't that at all. Specifically, archeologists believe Cleopatra suffered from excessive weight, and her family was to blame.
In the Ptolemy tradition, Cleopatra's family regularly practiced incest. Obesity in her family was exacerbated by the incest. On top of that, many believe she and her brother and sister were both afflicted with less-than-attractive features.
Princess Nahienaena Lost Her Baby Because Of Incest
Princess Nahienaena of Hawaii became romantically involved with her brother - King Kamehameha III since the two were children. But when she sought to marry him, Christian missionaries vocally opposed the union. They were never married, but did conceive a child. Unfortunately, because of complications many believe were do to incest, the baby only lived for a few hours.
Nahienaena never got over the child's passing and died shortly thereafter in 1836.