MTO- It's called Dominance Relationship and Recessive Genes.
President Warren Harding, J. Edgar Hoover, Carol Channing, the biracial daughter in the movie "Imitation of Life" and every OTHER person in history that has "passed" for Caucasian possess these genetic disorders.
Every human has two copies of each gene that makes up their DNA. In Victoria Rowell's case, her mother is White (Which gives you 2 sets of White genes); father is Black (Could possibly possess 2 sets of Black genes, presuming there is no Caucasian blood due to slave-trade rapes), and her daughter Maya's father, Tom Fahey, a Hollywood cinematographer/actor is White.
Victoria's son Jasper is the son of jazzman Wynton Marsalis, who presumably possesses the Black gene as his dominant one.
Therefore, if we breakdown the gene pool of the Fahey/Rowell/Marsalis clan, we have:
Mother (2 sets of WW gene) plus Father (2 sets of BB gene) equals
Victoria (2 sets of WB gene)
Then add Victoria's (2 sets of WB gene) plus Tom Fahey's (2 sets of WW gene, because his parents are BOTH White), and you get
Maya Fahey (3W 1B gene). In other words, the White gene is her Dominant Gene, and Black is her Recessive Gene.
If you perform the same exercise with Wynton and Victoria, you'll see that the White dominant gene stopped at Victoria, therefore giving Jasper the Black Dominant Gene and White as the Recessive Gene.
It's just science.