This myth is particularly popular in South America, including Brazil, Argentina, Uruguay, and Paraguay. According to legend, the seventh son of every family would become a cursed creature that wreaks havoc across the village.
In Argentina, the werewolf is known as “el lobison”, in Paraguay it goes by the name Luison, and in Brazil it’s called the Lobisomem.
The terrifying werewolf-like creature shows its true nature on the first Friday after the boy’s 13th birthday, the legend says, turning him into a demon at midnight during every full moon. The boy is then doomed to hunt and kill before returning to human form.
The horrific creature used to feed on excrements, unbaptized babies, and the flesh of the recently deceased. It was said to be unnaturally strong and able to spread its curse through bite wounds.
In Guaraní mythology, the werewolf-like creature is the offspring of the evil spirit, Tau, and Kerana, a mortal woman. In some cultures, that creature acts as a sort of Grim Reaper, whose mere presence means that death will soon befall those it comes into contact with.
The fear of this creature was so real in Argentina that it is said, in the past, families sometimes murdered their seventh sons to prevent the curse. In 1907, in an attempt to put an end to this practice, the Argentinean president began adopting seventh sons. According to him, this would make people stop believing the legend.
In 1973, for unknown reasons the tradition of presidential adoption was also extended to seventh daughters by Juan Domingo Peron who even made families baptize their seventh son.