Funnily enough, you were in the discussion I was referring to. But it was on the old PF.
@Hanover was in it too. It centred around the general status of AAVE/BVE.
This article gives a fairly straightforward picture of the linguistic angle I'd be closest to on the issue. Essentially the argument is that nigger/nigga are in an important sense different words rather than just differently pronounced variants of the same word (this shouldn't be particularly surprising if one recognizes the existence of AAVE and understands a little about how dialects/sociolects work. "Dope" and "sick" are words whose meaning can vary to the point of incomprehensibility to fellow English speakers not familiar with their dialectical use.)
Anyhow, here's the crucial point of departure for any sensible conversation on the issue:
"One of the most potent slurs in American English is the racial epithet nigger (we warned you!). However, many white people oblivious to history and privilege don't hesitate to muse, "why can they [read: "black" people] use it, then?"
Their observation - that some black Americans use what sounds like the same word - is valid, although insisting that makes the use of slurs OK is not valid."
...
"So when some speakers of AAVE use the word nigga, it is understandably interpreted as an r-less variant of a word that underlyingly has an r. However, the supposed r never shows up, not even intervocalically (jargon for "between vowels").
When people maintain that they're two different words, there seems to be good evidence for that.
Note to white people: This does not give you license to use either. If you do not speak AAVE, and chances are you don't, you don't get to use either word. You WILL offend people, and no one will like you."
My bolding. And this is not just opinion. It's backed up by mounds of evidence, some of which is mentioned in the article (pdf of original study
here ).
The authors go on to discuss the technical term "semantic bleaching", which refers to the phenomenon of words losing shades of meaning over time. "Nigga" is one such word.
Re this important point:
I happen know people in black London sub-cultures who have close white friends in those sub-cultures who use the word just like they themselves do. They know how to use it in a way Hanover never could, not only or even primarily because he's not black, but because he's not of that sub-culture. — jamalrob
It's addressed here:
"[Nigga] is not inherently specified for race, like nigger and other epithets are. In fact, race is often added to it, so the authors may be referred to in our neighborhoods as "that white nigga" and "the black nigga who was with him." Others include "asian nigga," and even "African nigga."
Among those who use the term, it is now a generic term like guy.
This shift in meaning seems to have happened some time after 1972-ish, possibly in conjunction with the rise of the Black Power movement, as an attempt to reclaim the word, similar to some feminists reclaiming bitch, and cunt. It was a necessary prerequisite for the super cool grammatical change our paper is actually about."
So, yes, it's not about skin colour or genes as such but being a member of a community broadly considered the black community but encompassing sub-cultures where you don't have to be black.
The article goes on to argue that "nigga" is actually becoming a pronoun rather than a noun and there's data to support that, but that's less relevant to the issue being discussed in this thread.