Why aren't I attracted to African American women?

A few days ago I was watching something on television( I cannot remember what it was). They were talking about how many black men nowadays are marrying or have girlfriends with different races of women (such as Latin, Caucasian, and Asia). Then I noticed I've never been attracted to any African American women before and i'm 17 years old. I'm of African American/Caucasian decent, but my parents and family are German( I'm adopted from birth). So the next day I asked my friend what he thought. He concluded that maybe Its just my environment. He's referring to the point we live in a predominately Caucasian suburb, school system and church. That's not to say there aren't any African American families here, but they are not as common as Caucasian or even Latino and Asian families here.And even so there are plenty African American women on television and the internet who are regarded as being hot or cute. I asked my dad what he thought about it and he said that everyone has their preference and I shouldn't feel bad about mine. My mother said the same as my father, but when I insisted on a different answer she said maybe because of the little diversity where we live could play a role in it. My brother has had only Caucasian girlfriends and one of my sisters has a Latino boyfriend. I guess my question is "Is it normal not to be attracted to your own race's women" "Is it my fault?" "Am I subconsciously avoiding African American women?" I just find it kind of weird. My girlfriend is Japanese so I am use to being attracted to diverse races. Is there anything the matter with me?