Thanks for the lead. Someone in another comment described it as an inverted pyramid. The graph of Cleopatra VII's lineage seems to be the best example of that:

Thanks for the lead. Someone in another comment described it as an inverted pyramid. The graph of Cleopatra VII's lineage seems to be the best example of that: https://en.m.wikipedia.org/wiki/Pedigree_collapse https://en.m.wikipedia.org/wiki/Pedigree_collapse