Earlier quoted context omitted.
Mannerisms could be anything from how articulate the candidate is and the depth of their vocabulary, to how they dress and the types of questions they ask. I’m not saying it’s okay to discriminate candidates by it, doesn’t mean it doesn’t happen. Go to any finance firm on Wall Street and tell me how many people employed there grew up on food stamps.
- Mannerisms could be anything from how articulate the candidate is and the depth of their vocabulary, to how they dress and the types of questions they ask. Those are all qualitative things that tell me about the person's intelligence, social acumen, experience, worldliness, etc. Those things usually matter for hiring. Has nothing to do with caste or race or gender or identity or age or sexual orientation any other…
You could say they're smarter because they're doing what's needed to game the system... but that's only needed because people are judging them on those aspects. Chicken or egg?
Does a thick German or Scandinavian accent count against them? What about Mexican/Spanish? What about Ebonics/Black English? That has well understood rules for how it's used, even though many people don't realize it.
Presumably what you actually care about when hiring is their ability to work well with their peers and managers, and how well they accomplish the work they are given. If so, you are using mannerisms to help inform about these attributes you actually care about because you think those mannerisms correlate in some way. But what do you have to go by to actually support this evidence? If it's from personal experience, how rigorous have you been in making sure you note the data, and didn't subconsciously discount or ignore instances counter to your expectations?