Jeff, by my ancestors, you mean the Portuguese Jesuits that built those missions and tried to protect the Indians from slavery, or do you mean the Brazilian and the Spanish colonists that were trying to enslave them?
Slavery is a mean thing: everybody did it.
The Arab Muslims that captured africans inland and brought them into the Magrebe.
The african rulers that went to war with other african people and them sold the captives to the Europeans stationed in the African coastline, at Mina, Ajuda and many other tiny possessions.
The Portuguese, Spanish, English, French, Danish, North-American shipowners that engajed in the most colossal people displacement that the world has ever known, bringing african slaves from Africa to the New World.
The moorish pirates that enslaved any European that they managed to lay their hands on, either by capturing them at high seas or invading Europe (the Azores, Madeira, Porto Santo, Canary, Mallorca, Ibiza, Menorca, Malta islands, and even the mainland, all the south of Portugal and Spain, and even Iceland, Ireland and Britain).
The European, by enslaving the moors that were captured at sea or while invading Europe - we even have a saying in Portugal, when you tire yourself to death with work: "I am working as much as a Moor".
Anyhow, past History is just History, you cannot judge it with your modern eyes, beliefs and moral settings. It was (still is, in some parts of the world, today) a violent life, sometimes a very brief life for the people that were our ancestors. Several centuries before the Americans bombed Tripoli, a Portuguese fleet did the same. The accounts are extraordinary: while the Barbary pirates were tying Portuguese prisoners and slaves to the muzzle of cannons, firing them afterwards from the city ramparts, in full face of the besieging fleet, the Portuguese were responding by nailing Ottoman prisioner to the masts and inserting pork bacon into their mouths...
And yes, I did see The Mission, although I rather prefer Aguirre or the Wrath of God, by Werner Herzog:
http://en.wikipedia.org/wiki/Aguirre,_the_Wrath_of_God;)
