I'm curious, how do you know a persons ethnic group or sexual orientation, or other categorizing group on stack overflow, unless you the person wants that infor

I'm curious, how do you know a persons ethnic group or sexual orientation, or other categorizing group on stack overflow, unless you the person wants that information out there? I can certainly understand some responses and/or behavior are troublesome, but i don't get the tie in between the bad answers tied to certain groups. Their certainly can be a superiority complex problem, but it seems to be more around people's sense of their mastery of a language, or technology, or coding style or whatever. I certainly haven't traveled to all corners of stackoverflow but have contributed a good bit, and yes, my java is better then your java (or whatever) is present, but is it really tied to people's identities?