In the old churchyard of Västerhus in northern Sweden, a young woman was buried with a scallop shell tucked beside her. That small shell — the same kind millions of pilgrims still carry today — tells an extraordinary story. She had walked thousands of kilometers across Europe to reach Santiago de Compostela in northwestern Spain, one of Christianity's most sacred destinations, and then returned home. She died before turning 30. Scientists call her Lady 56.

Scientists at Stockholm University have now read the DNA of 142 people buried in medieval graves across Sweden, and their findings are rewriting what we thought we knew about how Vikings and medieval Scandinavians treated their dead. The study, published in the journal Science Advances, looked at remains from three sites: Sigtuna near Stockholm, Västerhus in Jämtland, and Fjälkinge in Skåne. Among those 142 people were more than 60 children and teenagers.

When archaeologists find an adult and a child buried side by side, it's natural to assume they were parent and child. That was the common assumption. But the DNA told a different story. Close biological relatives — parents and children, siblings — were surprisingly rare among people sharing the same grave, even at cemeteries where other family connections could be detected.

"We often assume that adults and children sharing a grave were parents and children or other close family members," said Maja Krzewińska, the study's lead author. "In most cases, that was not what we found."

The researchers say this means other factors — perhaps friendship, community ties, or religious beliefs — shaped who ended up buried together, not just blood relation.

The study also revealed something striking about how children were treated in death. At Västerhus, where men and women were traditionally buried on opposite sides of the churchyard, boys and girls followed the same division. Even the youngest children were sorted by biological sex, suggesting that gender identity was recognized early in life.

"The children were not treated as a separate category," said Anders Götherström, a professor of molecular archaeology who worked on the study. "In death, they appear to have been treated according to the same social and religious principles as adult men and women."

DNA also confirmed that Lady 56 was connected to several relatives buried elsewhere in the same cemetery — her parents, her brother, and her two daughters. Her story is a reminder that the dead carry more secrets than we ever imagined.