When it comes to nature vs nurture, it's not one or the other, it's a combination of both. Only a simple minded fool thinks it's only cultural or solely genetic. Reality is more nuanced than that.
It's often be said that genetics load the gun but environment pulls the trigger.
My grandfather was born in 1906. As long as I knew him he never had a bad word to say about blacks, and he had known plenty living through segregation. To him they were always just colored folks. My dad on the other hand, being a baby boomer is not a fan, to put it mildly. He didn't inherent that attitude from his father, he learned it first hand. I myself have met few who didn't fit the negative stereotype.
Something cultural changed in this country during the middle of the last century. That trigger got pulled. Now we're dealing with the consequences because there's no way to put that genie back in the bottle. Even in my time I've seen race relations get much worse after Obama got elected. That was like pouring gasoline on the fire.
