I'm sorry but what in the actual hell are you talking about? The reason I didn't like most Slytherins is because they were cruel to me and my family, many of them also would have liked to see us dead - even told us that when things got pretty dicey or actively tried to kill us. Now, I realize that its difficult for you to come off of your self-absorbed entitlement and 'woe is me' attitude but there are also a few Slytherins in the world who did a great service to Harry and my family, people without whom we likely would not be here.
But I'm not surprised, of course you would only think that we would raise our children to be prejudice. That two people who fought in a war, who had friends and family die in a war that was born from one man's hatred of others, might not have learned a thing or two about the cost of ignorance. That the price of treating anyone as less than a human only breeds hatred, and creates a world where people die for something as simple as who their parents are and what type of "blood" runs through them. I mean how could we possibly learn anything, we were oh so busy talking about how mean and horrible all the Slytherins were. How they ruined all of our lives.
Except that didn't happen - Death Eaters? They might have found an origin in your House, but they did not make up all of them. Gryffindors were Death Eaters. Hufflepuffs and Ravenclaws as well. Likewise, there were Slytherins who believed in Harry, who fought for what I believe to be the right side. Don't you DARE whitewash everything that happened and paint it over in the color of the Hogwarts Houses so you can feel justified for whatever misplaced issues you have.
My children have been raised to respect everyone. To understand that every single person in this world - be they magical or muggle, Slytherin or Gryffindor, werewolf or human is worth something. Do they have to agree with everyone? Of course not, they all have their own ideals and their own beliefs, but I hope they respect them and try to understand how a person ended up where they are - even someone like Voldemort.