The Tedjin, Soriyan, Bozishnarud, Nafarati, Gai, Sandmen, Rhunnic, and Noi Trevan ethnicities all lack facial variability compared to other Mannish ethnicities like Rohirrim, Bellakaze, or Haradrim. Going into the Ruler Designer and clicking to randomize on any of these ethnicities creates very similar characters, as though they are all siblings. It looks to me like ethnicities have been borrowed from EPE, maybe with some small alterations. If that is the case, then it is also the cause of the similarity in appearance because of how EPE works.
The way that Celticus creates an ethnicity file for EPE is that he designs one portrait and then adds a small range around the gene values for that single portrait. No culture is assigned only one of these ethnicities. Instead, Celticus does this for a variety of manually designed portraits and assigns many such ethnicities to a culture (some cultures get over a hundred ethnicities assigned). That way, when characters of the culture are generated, they have a good variety of appearances. Without that, you get poorly disguised clone armies.
The Tedjin, Soriyan, Bozishnarud, Nafarati, Gai, Sandmen, Rhunnic, and Noi Trevan ethnicities all lack facial variability compared to other Mannish ethnicities like Rohirrim, Bellakaze, or Haradrim. Going into the Ruler Designer and clicking to randomize on any of these ethnicities creates very similar characters, as though they are all siblings. It looks to me like ethnicities have been borrowed from EPE, maybe with some small alterations. If that is the case, then it is also the cause of the similarity in appearance because of how EPE works.
The way that Celticus creates an ethnicity file for EPE is that he designs one portrait and then adds a small range around the gene values for that single portrait. No culture is assigned only one of these ethnicities. Instead, Celticus does this for a variety of manually designed portraits and assigns many such ethnicities to a culture (some cultures get over a hundred ethnicities assigned). That way, when characters of the culture are generated, they have a good variety of appearances. Without that, you get poorly disguised clone armies.
If the lack of variability is not something that you have noticed yourself, I recorded some videos to try and illustrate it. Here are some examples of the Bozishnarud and Rhunnic ethnicities: https://github.com/jj248/RealmsInExile/assets/18605346/eb29eb43-7536-4b11-a32a-7206f50051e1 and here are the much more varied examples of Bellakaze and Dunedain ethnicities: https://github.com/jj248/RealmsInExile/assets/18605346/b8a03a9c-e002-4ba6-bf79-2f04dfdc1625 Do you see how the characters from the second video had different eyes, noses, and mouths, while everyone in the first video had matching facial features to the others of their ethnicity?