Some 4,000 years ago in Bronze Age Greece, it was "customary" for first cousins to marry each other, according to a new study.
Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig in Germany, as well as international partners, analyzed genetic material from the bones of Bronze Age people from the Aegean islands. They were able to reconstruct the family tree of Mycenaeans from the mainland as well as Minoan civilization inhabitants from Crete island.
Philipp Stockhammer, one of the lead researchers, said genetic data showed cousin-to-cousin marriages.
"It’s too many people doing it to say it’s pure chance—but it isn’t 100%," Stockhammer said. "I would say it was quite a strict practice."
Moreover, fellow lead researcher Eirini Skourtanioti said such a "strict system" of kin marriage didn't exist anywhere else in the ancient world.
Researchers said it's probably because of economic reasons, i.e., to prevent family land from being divided.
"[I]t guaranteed a certain continuity of the family in one place, which is an important prerequisite for the cultivation of olives and grapes, for example," Stockhammer noted. “If you marry in your family, it means that you focus on staying in the same area.”
They also found that sons still lived with their parents during adulthood. Their children were buried in a tomb under the courtyard of the estate.
One of the wives who married into the house also brought her sister into the family, and her child was also buried in the same grave.
"What is certain is that the analysis of ancient genomes will continue to provide us with fantastic, new insights into ancient family structures in the future," Skourtanioti added.
In modern times, incest is considered taboo and even a crime. Aside from morality concerns, there are also scientific claims that children born out of such relationships might have birth defects.