Give me the names of someones white great great grandparents who were living in a slaveholding state and I will produce, in short order, the names of their slave owning ancestors. While most white folks living in the south did not own slaves, they all had relations or ancestors who did.
What is much more interesting is the number of blacks and Indians with slave owning ancestors. I think that most people would be quite surprised with the results of that research.
I point out in my history classes that we all had ancestors who were slaves--and ancestors who were slaveowners--either in this country or further back. For example, my first American ancestor was a slave, and he was "white".
Yes, Blacks (when they had the opportunity to do so) owned Black slaves. Read for example the famous diary of the "Barber of Natchez', a free Black who owned, and beat, his Black slaves. As did American Indians. Chief "John Ross", for example, had over 100 slaves on his plantation in what is now OK.