Personally, I think the saga about Thomas Jefferson and Sally Hemings demonstrated that DNA could certainly be used to figure out or prove family connections. Although many of the white Jeffersons may have been in denial about Thomas Jefferson's sexual relationship with Sally Hemings, many African-Americans believed the story the African-American Hemings and Woodson families were passing down about their ancestral tie to Thomas Jefferson because so many of us have similar situations in our family histories. When the DNA proved that Jefferson had a sexual relationship with Sally, resulting in the birth of at least one of Sally's children, it really increased the confidence in using DNA to determine kinship connections. I believe that in the minds of many African-Americans, the Jefferson/Hemings DNA results said "I told you so."
Just my 2 Cents,