Ancient DNA analysis sheds light on two individuals buried in a mutual embrace at the Exaltation of the Holy Cross Cathedral in Opole, Poland

Double and multiple burials offer rare insights into social bonds and funerary ideology. Often, the interment of multiple individuals in a common burial pit is interpreted as reflecting social or biological bonds that connected the deceased in life. When an adult and a child are buried together, the individuals are commonly treated as biologically related, while mixed-sex adult burials are interpreted as married couples. These assumptions, however, almost always require revision. Family structures and interpersonal relationships are complex and are not always unambiguously expressed in funerary practice. In this context, modern research techniques, particularly ancient DNA (aDNA) analysis, can reveal basic biological parameters, such as genetic sex and kinship between individuals buried in a common grave. Here, we integrate ancient DNA data with osteological and archaeological evidence to re-evaluate a unique double burial of two adults discovered adjacent to the 13th-century Cathedral of the Exaltation of the Holy Cross in Opole, Poland. This burial represents the first genetically confirmed same-sex burial in medieval Poland. By combining genetic and contextual evidence, we move beyond traditional assumptions of conjugal or close-kin relationships. Burials of mixed-sex adults are frequently interpreted as married couples, although such cases often require critical reassessment. In this paper, the term ‘same-sex burial’ refers to biological sex as determined by genetic analyses and does not imply gender identity, sexual orientation, or socially constructed categories. Several burials initially interpreted as those of ‘lovers’ have, following molecular sex determination, been reclassified as same-sex interments. For instance, the ‘Lovers of Modena’ were identified as males based on the presence of AMELY peptides in the enamel proteome, a robust biomolecular marker of biological sex (Lugli et al., 2019). Similarly, individuals known as ‘Hasanlu lovers’, two individuals buried in an embrace perceived as ‘intimate’, appeared to both be genetically male (Selinsky, 2017). The examples cited here are not intended as an exhaustive review of double burials, but rather as illustrative cases where biomolecular analyses have substantially revised previous interpretations based on burial position or morphology alone. Ancient DNA studies have proved that molecular data can fundamentally revise assumptions about interpersonal relationships in shared burials. Yet, systematic molecular validation of such burials remains limited, and interpretations of double/multiple graves continue to rely on morphological and contextual observations. In this study, we present archaeological, osteological and molecular evidence from a double burial excavated at the Cathedral Church of the Exaltation of the Holy Cross in Opole, Poland. The grave contained two adult individuals buried in a mutual embrace. Due to their atypical burial position, these individuals were quickly dubbed the ‘hugging skeletons’ and interpreted as lovers. Our work aims to interpret this atypical burial in the context of genetic kinship and sex, as well as the archaeological data. We show that both individuals are genetically females and unrelated, providing the first genetically confirmed same-sex double burial from medieval Poland.