There is a very old belief that someone who was born on Christmas is a werewolf. In many European countries it's believed that if a child is born during Yule and on Christmas eve and Christmas day, they would most likely become a werewolf when they grow up. Certain rituals would have to occur early on while the person is still a baby to prevent this curse developing.
This may be linked to the idea that the Winter Solstice was connected to pre-Christian beliefs in the old gods, and so Christmas time became linked to werewolves and other supernatural creatures and spirits. Most of all, the festive season today reminds everyone of elves, gnomes, fairies, angels and even ghosts. Monsters like werewolves are not just confined to Halloween period but tend to reveal themselves over Christmas.
During the 15th century, a Swedish explorer named Olaus Magnus, travelled to places like Lithuania, Latvia and Prussia, and in those places he encountered packs of werewolves. He described them as gathering together at Christmas as though they were having a party! He found that they resembled wolves but had transformed this way from men. They were responsible for the many killings of humans and livestock in nearby villages. He mentioned they were different to regular wolves in many ways, because they could speak and drank beer. When these werewolves attacked villages, they also raided beer cellars.
What else Magnus wrote about his travels, was the story of a disabled boy in Livonia, who travelled alone on Christmas, making friends with people, who were followers of Satan and there was many of them. It was believed violence occurred among them with an iron whip, and they revealed themselves to be wolves, that descended upon livestock animals and even people with bloodshed.
Wolf Girl Night