I'm surprised that none have mixed sons.
I recall a couple of years ago, I don't remember where, I saw a statistic that showed that most women but especially white women, were interested in potentially having a sexual encounter with a black man over men of any other race different from theirs. The other races had very low numbers, it wasn't even close.
However, among the many statistics one of them showed that women of all races seemed to overwhelmingly prefer white men for relationships and for having children. No qualifier. It seemed that although white women were DTF with black men, relationships and children were basically out of the question with a very low amount of white women considering it at all. If I recall this was significantly worse for women of other races, including black women if they could help it.
I'm going off of memory and it was a very long time ago, but I'm fairly confident that this still holds up. This would explain why even prostitutes follow the trend.