Going back to the notion of preference, it is highly unlikely that phenotype based preference is biologically preconditioned; Scientifically speaking there are three main characteristics through which we classify ourselves and others, Zenotype, Phenotype, and Genotype. Zenotype refers to psychological paradigm a mind set or mental aspect, phenotype refers to physical differences such as skin color, genotype refers to non-noticeable genetic characteristics. In order to find the root causes of such social conditioning one would have to start at the beginig, but that's for another post. Since our early beginings America has been plagued by this grotesque European ideology of white supremacy. Sadly this is a common occurance in any European-dominated society; just go to your google search engine and type in the phrase "All American Guy" and see what comes up. Psychologically speaking this sort of thinking is not engrained in us from birth (contrary to popular belief we are not born with our ideal partner in mind), preference is a learned behavior. This means that such behavior is nurture instead of nature, and more likely to be a product of environmental factors; such as were one grows up, were one goes to school, what kind of neighborhood they live in. it goes without saying that we are as the world has made us, to think that just because one is a minority that they're exempt from bias and prejudice is a very false statement.