As off-putting as it may sound, traits and appearance are “fixed” via inbreeding in people just as any other mammal selectively bred whether due to unintentional genetic bottlenecks or due to other considerations, sometimes this has been intentional as in the instance of royals or people of great wealth looking to keep inheritance in the family. Those descendants can look alarmingly like the very old portrait hanging on the wall, particularly among males. I’ve mentioned my late grandmother’s attorney and his resemblance. I also had friends in my teens, identical twins, who looked exactly like their 2nd great grandfather whose portrait was hanging on the mantel of their parents’ home. I’d think this would be a distinct possibility among descendants of First Families and other early settlers, they’d have been there for 150 years or more by the era in question.
If I recall correctly, such a resemblance was a clue in Conan Doyle’s The Hound of the Baskervilles and in some other mysteries (not noted until later).