Oh, THIS!!!! I was, as you know, adopted and people would often say, "but Bruce (my brother) is your REAL child, right?" Given that my adoptive parents were Black and so was my brother, it was pretty obvious that he was indeed their biological child. But obviously I was their REAL child. I was a real child and they had the paperwork on me, so to speak.
My father always dealt with stupid statements/questions like that with an equally stupid response. Something like, "yeah, Bruce is real, but this one, we gotta change the batteries every couple weeks," or something equally insane.