You could be describing me and my sister, but with a few twists. We, my sister and I are mixed race, though we are both white presenting. Sh is 18 months older than me. When out birth mother died, we were divided among relatives. She was raised by our birth father (save the year our uncle and my adopted father too us all in). She does the AAVE thing and identifies as Black. She fits the stereotype you speak of. I do not. She has ridiculed me over the years for plauin white when all I was doing was getting an education. I've tried over the years to have a relationship with her but it never lasts long. The truth is she's very troubled. She makes fun of me but then lies about her life, which somehow magically parallels mine. She's a pathological liar and a con artist. I went low contact and then no contact. I will never have a thing to do with her again. She's toxic and life is just too short.