Donald Trump and Scott Brown are ignorant of how DNA works. After a few generations, and purely by luck, a brother can show a little American Indian DNA and his full brother may not. There is massive documentation of my Indian ancestry in the Dawes Commission and in the testimony of family members, but my Ancestry.com showed 100% European. The great marine biologist Roger Payne recently explained to me how few generations it can take for DNA to disappear. Well, I lived most of my 80 years knowing obviously part-Indian family members. One very dark great aunt who said her grandmother was a "Chockie" (Choctaw) lived in three centuries, but not very long in two of them, so she was around in 2001. I got the blonde European side, and not a trace of Choctaw or Cherokee in that DNA test. So Elizabeth Warren may have had the same Oklahoma history. Scott Brown had a really long thin cute body when he posed naked, but he does not have great knowledge of human biology. And Trump is--well, ask Elizabeth Warren.
Today Philip Bump has a clear scientific piece on this in the Washington POST.