Go back far enough they probably all interlink anyway.
This is a bit difficult to explain, and I'm not sure I should boast about it. My grandfather came from a moderately isolated Derbyshire village. Tracing his ancestors, there are 6 separate cases where pairs of ancestors are siblings. That is, 6 cases where I can trace up either of 2 branches to reach the same point.
I have some gaps in the tree, but I do know that whereas he should have had 256 5g grandparents, there can be at most 192.
