Okay, in this hypothetical, let's just assume the bloodlines are pure. If you have someone who is 100% white (W) who has a child with someone who is 100% black (B) they would have a child who was 50% white and 50% black (WB). So then let's say that person has a child with someone who is 100% black, so the child would be WBB, then repeating that, WBBB, again WBBBB. At this stage if we kept repeating this scenario, would the new child ever be 100% black again or further down the line if we continue this, for 10 generations, or will they always be considered to be 0.0001% White even if the ensuing children only ever had children with someone else who was 100% of that other race?
Most Helpful Guy
Past ancestry NEVER disappears. The recessive traits (white) in your example will always remain with that person regardless of how black their parents, grandparents, and great grandparent were. African Americans are a prime example of this.
African Americans on average are mulattoes with about 15-25% European ancestry. Majority of that European ancestry was introduced to them over 100 years ago. Even though African Americans are technically "biracial", their white trait doesn't show up physically because the white side has been diluted after generations of constant breeding with other black people. However, just because it's been diluted over the centuries doesn't mean it's not there, because it is there and it will forever stay in that person's families' genetics until the end of the world
Physical traits can disappear but genes do not. :)3