Slavery and slave owners

At a recent literary party we had a number of  poets reading their work. One of them, I am afraid I don't remember her name, read a long and impassioned tirade about her Slave ancestors. Why, I wondered,did this annoy me and make me uncomfortable. Thinking about it I realise that it is because poems like this are intended to make pale people like me feel guilty for having slave-owner ancestors. Yes, indeed I did have ancestors who lived on St Helena and were owners of slaves, and most unsavoury characters they were too. I have recently been researching them on Google and have been quite shocked at what they were capable of. But what my researches also turned up was that not all my forbears were lily white. Some of them were definitely rather dark of complexion and must have been the offspring of black African slaves. So now I can also lay claim to slave ancestors and I can stop feeling ashamed and get all indignant instead. And, come to think of it, the poet in question, was not nearly as dark as the West Africans that were brought into the Cape in the early days. Could she carry in her veins the blood of  at least one wicked Slave owner? How much of that evil person's nature did she inherit? Shouldn't she also feel shame?