It's extremely sad that some people think this way in 2015.
I 've even experienced it myself, when I had an Iranian girlfriend. When we walked hand in hand where I live, which is in a sort of ghetto with a lot of middle eastern people, we often experienced people yelling at her for not sticking to a man "her own race and religion" as they said. (I'm white as can be, and she was an atheist like myself).
I even heard some lady whispering this to her husband once when me and my ex was out grocery shopping: "God, I hope those two don't have children. Wouldn't want to mix those fine Danish genes with those dirty genes she's carrying around".
The fact that racist ignorance still is quite visible in 2015 is mindboggling, IMO.