The man buried in the inner chamber of Newgrange was the son of a brother and sister or a parent and child

Newgrange is a passage tomb built about 5,000 years ago, aligned so the winter-solstice sunrise lights its inner chamber. Inside, in the most elaborately carved recess, excavators found unburnt, scattered human bone, including the skull of an adult man. Trinity College Dublin geneticists sequenced 44 Irish Neolithic genomes and published in Nature in June 2020. The man, catalogued NG10, had long runs of identical DNA covering a quarter of his genome. His parents were first-degree relatives: full siblings or parent and child. The DNA cannot say which. The authors note that such unions are accepted almost only among sibling pairs in polygynous royal families headed by god-kings. Given where he was buried, they argue his parentage was socially sanctioned. NG10 was distantly related to people buried in the Carrowmore and Carrowkeel passage tombs 150 kilometres west, the earliest of them in the founding monument at Carrowmore. Passage-tomb people also ate differently from other Neolithic people sampled. Middle Irish lore, written down in the 11th century, tells of a builder-king who restarts the sun by sleeping with his sister, and calls the neighbouring Dowth tomb a name that translates as Hill of Sin or Hill of Incest. Lead author Lara Cassidy said she had "never seen anything like it." Dan Bradley described a hierarchy in which only family members were worthy partners for the elite. Alison Sheridan of National Museums Scotland questioned other parts of the paper.