"I have always kind of been ashamed of that, in a way- as my ancestors have been involved in some really unethical sh*t over the centuries. Genocide, etc."
Thre is no reason for you to be ashamed. You have no control over what your progenitors, or anybody, did in the past, and no responsibility. If you have specific knowledge that a specific ancestor, from whom you inherited property, stole the property, you might want to consider somehow returning it, or something of equal value, to the heirs of whomever he stole it from. But you are not legally or morally, in my opinion, under any obligation to do so. And you certainly should not apologise for something that somebody else did. Now if your children harm someone, you have some responsibility for what they do.
People doing things that are unethical and immoral, just because they had the power to do so and get away with it, have belonged to numerous ethnic group, and numerous genetic varieties. Immorality is hardly something that the white man invented.
Some simplistic people like to talk about slavery in the United States, as if white people did the enslaving, and black people were the enslaved but this is simply not the whole truth. The center of the slave trade of Africans, in Lagos, was a center of slave trade before white Europeans discovered it. Black people of one social status, or ethnic group, or genetic group, bought and sold black people of other social classes, ethnic groups, and genetic makeup. Black parents traded sold their children, or gave their children to creditors in return for having the loan cleared.
At one point, one pope told the portugese traders who saw the lively slave market, and wanted some of the merchandising action for themselves, that they could not buy slaves from people did not normally trade in slaves, and that it was only ethical to buy or seize people for trading as slaves, from ethnic groups who had slave-trading as part of their culture, and might have sold the children that the Portugese traders was considering buy, or steal, to some other black person, if the white Portugese traders didn't buy them first. No doubt some of the portugese traders were convinced that should these people be sold to another black ethnic group, or to another class-ranking within the same group, that they might be treated worse than if they were sold to white Europeans or white new-world buyers.
Of course this is just a pretext to assuage some of the guilt they felt about trading in slaves. And of course many traders didn't exactly follow the pope's prescription meticulously. I'm just trying to make the point that things aren't as simple as high-school teachers like to make it for high school students.
I believe the Aztecs of higher classes owned slaves of lower classes. The north american pre-Columbians did not appear to trade in slaves, but they did sometimes use force to make other N americans pre-columbians people to perform labor, for years, without allowing them to keep the products of their labor.