None of my ancestors ownes slaves. Why am I to blame for slavery?

Quit guilting yourself over slavery. The mistake your ancestors made was in coming to a country where the damage caused by slavery had to be repaired. Whether or not Affirmative Action will succeed in repairing it is another question altogether - the point is that whites have enjoyed the fruits of slave labor, including the very system that supported it, for centuries, at the expense of blacks. If you want to grudge them this attempt to include black people in the economic life of the nation, you should come up with a better solution, not paint yourself as a victim.