They didn’t issue birth certificates or record births in family bibles for slaves on plantations. Lots of female slaves gave birth to children fathered by their masters or other white males. Most of “African Americans” have European and even indigenous American in addition to African ancestors. Based on phenotype, Meghan Markle appears to have quite a bit of European ancestry in beyond just her father.
If you are going to use big words, look up their definitions first.