In 1966 if you asked for bread you got white. I was told as late as the mid 80s by one black woman from St. Louis that she didn’t understand why Whites had a thing for wheat & rye bread. She said bread is *supposed* to be white, and suggested it was all about plain White people acting ethnic. Perhaps the marketer had done studies that confirmed that and figured they would market for the existing preference in the Black community, rather than try to change it? I don’t remember when I first heard the expression “white-bred” but I don’t think it was as early as 1966. I’m guessing it was the 70s before people were using that much.