I remember old Southern whites had a thing about how just a little bit of black blood in your family history was a scandalous thing. VJ, if I understand correctly, has one black grandfather in her genealogy. She really doesn’t appear “black”, but the modern day racists have a new take on the “one drop of black blood” way of thinking.
The term, African-American, is used to describe anyone descended from African slaves who came to America before the Civil War. Freedmen and house slaves, who were largely the predecessors of the future black upper classes, were more likely to have some white, usually British, ancestry, mainly due to illicit relationships. From the beginning of black society, the African-American elite tended to have some degree of white ancestry. Frederick Douglass had American Indian and European ancestry. Booker T. Washington's father was a white man, ancestry evident in his green eyes. W.E.B DuBois was a mulatto, with English, Dutch, and French ancestry on both sides of his family. For several generations, the upper class among African Americans generally had some degree of white ancestry. The elite clubs and college fraternities that catered to well off blacks exercised the "paper bag test" where admission was granted only to those whose skin tone was lighter than the bag. Actors and actresses in movies that catered to African American audiences (and were among the first crossover actors in mainstream movies) often had markedly European features: Lena Horne, Dorothy Dandridge, Harry Belafonte.
Valerie Jarrett comes, on both sides of her family, from the black elite. She has a Ashkenazi Jewish great-grandfather, but the rest of her lineage is African American. Her mostly European features likely do not come from the 12.5% of her lineage that is Caucasian, but from mixed race relationships that occurred several generations back.
Her background, unfortunately, allowed her parents, and probably her grandparents, to connect with the white liberal establishment. Like Barack Obama (not a traditional African American, at least if the Barack Obama, Sr., parentage is true), she was a "red diaper baby" exposed to leftism from the start, not much different from Bill Ayers or Bernadine Dohrn.