If you have any cousins that register as African-American, it's because their line remarried into African-Americans much later on. I think Parthena is at least 12 generations back for most people and her children remarried into Caucasian families (the story says they had all the benefits of white people and remarried into white families). So Parthena's lineage wouldn't affect you having black cousins. Only more recent bloodlines would. Besides, you need to give a name and birth/death information.