A tree is a terrible representation since people will appear in more than one place on it. brother sisters marriages (which did happen) tend to produce deformed kids, but first cousins have good odds for normal kids. By third cousin odds of genetic issues was close enough to zero, but those kids will have six great great grand parents not the mathematical eight. I didn’t mention half siblings but that happens too and a couple generations below could marry safely.
the above isn’t just theoretical. Before modern transport you often lived and married in the same village for many generations. It would often be impossible to find anyone to have kids with that wasn’t at least sixth cousins from more than one path.
There is at least one Menards with a railroad siding, or at least was 20 years ago when I lived in the area. (oakdale mn) I undrestand some deliveries came via rail to that store and them by truck to the rest of