The article is citing the Bustamante report. That's her expert, Carlos Bustamante a geneticist at Stanford.
WAPO is basing its reporting on the Bustamante Report and on data from University of California Davis. Bustamante's Report suggests a single ancestor
WAPOs interpretation of UC Davis's information leads them to believe that the ancestor is more recent
I don't know why Bustamante would need to respond to inaccurate reporting, his report and basic math speak for themselves.
Here's the report itself:
http://templatelab.com/bustamante-report-2018/
Earlier in the thread, someone posted a partial genealogy of Warren going back to and a little before the period of the Trail of Tears. She had ancestors back then living in Tennessee and Kentucky who had the surname "Clark". There were also Cherokee people living in those States who also had the Surname "Clark".
It is possible that her ancestry dates back that far, to an American Indian who married into a white family which then used influence to avoid going on the Trail of Tears, to the point of forging away any connection to tribal membership. The connection to Oklahoma may be little more than a coincidence as regards the ancestry. Her ancestry covers a good part of many places where Cherokee and other tribal groups that were later displaced to Oklahoma once lived.
However, gossip can survive a few forgeries, it seems likely that people might still have known about Native American ancestry even if it didn't appear on Birth Certificates or Baptism records. Showing bias against someone as little as 1/4 American Indian would not have been uncommon, showing bias against someone because that person's mother was 1/4 American Indian would not have been uncommon. Warren alleges that her parents faced difficulties because one of them was believed to be
part Native American - that still seems possible to me.
My opinion:
1: Warren is not Native American because her ancestors did not continue any sort of cultural affiliation or membership with any tribal groups.
2: Therefore, she should not have claimed to be Native American on paperwork, even if it provided her no advantage. She was lying when she checked those boxes on forms, although she may have been lying to herself in the process.
3: She does, however, have Native American ancestry, proven incontrovertibly and consistent with her family lore. She was probably not lying about the family lore.
She was right on this issue, and she was wrong on this issue. People seeking black and white right/wrong judgments on her behavior will therefore be forever frustrated.