Johnny Depp is 3/2048ths African-American (his great-great-great-great-great-great-great-great-grandmother is Elizabeth Key (Half African-American) and great-great-great-great-great-great-great-great-grandfather is William Grinstead).
Laurence Herman "Gus" Versluis was 3/2048ths African-American (his great-great-great-great-great-great-great-great-grandmother was Elizabeth Key (Half African-American) and great-great-great-great-great-great-great-great-grandfather was William Grinstead).
Any other Grinsteads could be part African-American.