In 2021, we published the results of genomic analyses carried out on the famous bishop of Lund, Peder Winstrup, and the mummified remains of a 5–6-month-old fetus discovered in the same burial. We concluded that the two individuals were second-degree relatives and explored the genealogy of Peder Winstrup to further understand the possible relation between them. Through this analysis, we found that the boy was most probably Winstrup’s grandson and that the two were equally likely related either through Winstrup’s son, Peder, or his daughter, Anna Maria von Böhnen. To further resolve the specific kinship relation, we generated more genomic data from both Winstrup and the boy and implemented more recently published analytical tools in detailed Y chromosome- and X chromosome-based kinship analyses to distinguish between the competing hypotheses regarding maternal and paternal relatedness. We found that the individuals’ Y chromosome lineages belonged to different sub-lineages and that the X-chromosomal kinship coefficient calculated between the two individuals were elevated, suggesting a grandparent–grandchild relation through a female, i.e., Anna Maria von Böhnen. Finally, we also performed metagenomic analyses, which did not identify any pathogens that could be unambiguously associated with the fatalities.