For others and me: [NOTE: no contents are changed, per scholarly rules.]
https://en.wikipedia.org/wiki/Pedigree_collapse
"How it works
Without pedigree collapse, a person's ancestor tree is a binary tree, formed by the person, the parents (2), the grandparents (4), great-grandparents (8), and so on. However, the number of individuals in such a tree grows exponentially and will eventually become impossibly high. For example, a single individual alive today would, over 30 generations going back to the High Middle Ages, have 2 30 {\displaystyle 2^{30}} or roughly a billion ancestors, more than the total world population at the time.[2][pages needed]
This apparent paradox is explained by shared ancestors, referred to as pedigree collapse. Instead of consisting of all different individuals, a tree may have multiple places occupied by a single individual. This typically happens when the parents of an ancestor are related to each other (sometimes unbeknownst to themselves).[3][4] For example, the offspring of two first cousins has at most only six great-grandparents instead of the normal eight. This reduction in the number of ancestors is pedigree collapse."
We still need to know how to handle the app to begin fixing things, Jamie. It's probably simple, but not obvious to some of us.
