Relationships between slaves and slave owners can never really be consensual, IMHO. There may not be physical rape involved in all cases, but when the man holds all power over the woman (including selling her, her family, and her children away from each other) how can she be said to be making a free choice?
You make valid points here and I wasn't saying that relationships between slave holders and slaves were free choices for the slave the way we in the early 21st century would consider free choices. However; I consider that some were cases of slaves making the best of a bad situation that they had been subjected to against their will via capture or birth. Put it this way: which relationship would have had more potential to a slave woman: one with a slaveholder who'd expressed his interest who could decide to keep one's offspring on the plantation and have them work as 'house servants' or a field hand expressing interest who themselves would have no determination in their children's fates and could be sold away or beaten to death? And then,too, even in times and situations where the majority of folks have been encouraged to hate and fear those who are different, there are some from differing groups who defy conventions to actually become physically attracted and even fall in love long enough to conceive despite the odds going entirely against any long term benefit. For the sake of their descendents, I think Professor Gates should have at least been willing to consider the possibility of more positive conception MO as opposed to uniformly encouraging them to believe that there was no chance that their ancestresses had had anything but forced conceptions.