Disagee. Babies and even small children don't discriminate based on skin color, yet babies and small children are the most vulnerable. (And there are instinctive fears, such as of loud noises.) Small children can see that others are different, but have to be taught that different means bad.
I think a lot of instincts come from the basic instinct to mimic. I take your point though, and it relates to my own experience.
I was a 'babe' when it came to understanding why people are racist until I was in my late teens. I grew up in a lily-white neighborhood, and never saw anyone of another race except in books. Those biographies of Martin Luther King made me see that differences can be embraced, and even bring strength and heroics.
A black family moved in when I was in 5th grade. The children were in my grade and younger and were welcomed readily at school. The girl in my grade ran for class president and won. She aced her classes like it was nothing.
The next year they were gone though, and I asked my dad why a whole family would move in only to move out a year later. He told me that the parents were harassed into moving, and that the local police were apparently looking the other way. It made no sense to me that any of this had happened (I later learned that the city - in coastal southern CA - had a law on the books until the '70's that said if you were black and didn't live or work in the city, you weren't allowed to travel through the city).
My job after high school was for a local large retailer (Gemco), and my boss approached me one day to follow him outside. He said that we were going to help catch a shoplifter. I asked what he looked like, and he said, "It's a spook." I said, "What's that?" He told me and I could see the hatred in his response.
We waited outside the store and when the shoplifter came out, he was approached by about five of us. He tried to run. My boss grabbed his arm which swung his back directly into me. And my boss yelled, "Grab him!" So I put my arms around his torso, and my boss proceeded to give him a pummeling until someone in the crowd that had formed pulled him off.
Racism became suddenly very real. As I always do, I try to determine peoples' motivations, and I'm sure poverty drove that man to steal groceries, and I know the store cannot stand for that, yet I sympathized; if it wasn't for that job I don't know what I would have done.
Now I see racism on all sides and in a lot of places (even on comedy shows), which leads me to believe in my instinct theory, even if the basic racism instinct is born from the core instinct to mimic.