Earlier quoted context omitted.
That tree's focused on only one person, Ben Stacy; his ancestors. The entire tree sounds a lot more connected: > However, by the early 1960s, some members of the Fugate clan had begun to resent their cobalt-tinted skin. Not only did their skin mark them as different, but by that time, people had already begun to associate their skin color with the family’s history of inbreeding .
I think if any of us had a visual cue showing our familial ties people would also say we had a family history of inbreeding.
It’s called pedigree collapse. Your family tree grows exponentially to the second power with each generation. So a mere 50 generations ago, which is to say roughly 1000-1500 years ago, you had 1,125,899,906,842,624 slots in your family tree. Needless to say the vast majority of those slots don't have a unique person in them.