Some people in this thread were exaggerating Amhara ethnic diversity as if it was similar to Sudanese Arabs (e.g. Bataheen vs Messiria).
There are probably more outliers among Somalis than among the Amhara,

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Look at this study, Amharas and West-Central Oromos nearly the same (most highlander Ethiopians are relatively similar), while Somalia North and Somalia South show a big difference:
Background Human population history in the Holocene was profoundly impacted by changes in lifestyle following the invention and adoption of food-production practices. These changes triggered significant increases in population sizes and expansions over large distances. Here we investigate the...
link.springer.com