Given the BSA is 108 years old, I would think 5 generations of Eagles in a family would be the limit. I have not found 5 generations yet, though I have found other interesting combinations: 25 Eagles in 3 generations http://www.tallahasseemagazine.com/March-April-2010/A-Nest-of-Eagles/ 15 Eagles in one family https://www.mycentraljersey.com/story/news/local/outreach/caring-communities/2017/06/30/east-brunswick-family-has-landed-15-eagle-scouts-and-counting/388949001/