I never really questioned my fondness for black women, I just kinda went with it. If I had to guess I'd say it's because the first friend I remember having was a black girl who lived down the block from me. I was about four years old.
Not only that, I went to a high school where about 85% of the student body was black. Not to mention one of the true loves of my life is black. So if I ever had to explain why I prefer black women over any others, it's probably because I've grown up around them.