I was born into a whole lot of dominant groups in my society (95+% anglo suburb, never met an open queer person until 18yo, you get the picture).
Being in the intersection of socially-dominant groups, I suspect this affects the range of mainstream in-group politics, since there are plenty of people who want to conserve dominance, and since there is more social power there for propagandists to prey on.
Consider the White family Thanksgiving stereotype, with the racist unkkkle, the progressive/socialist niece, and everything in-between.
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In minority groups, whether it be race, gender/sex, disability, certain jobs, religion, etc., is there more uniformity of politics? Or is it still common to see people spread out across progressive and reactionary positions?