Abigail Adams nee Baxter (1634-1692) was the paternal great-grandmother of John Adams Jr., second president of the United States.
Born: Sep 1634 in Roxbury, Suffok County, Massachusetts to Abigail Baxter was born on September 28, 1634 in Braintree, Massachusetts Bay Colony. Her parents were Gregory Baxter
and Margaret _____. 
Married: Joseph Adams in Braintree, Massachusetts on 2 Nov 1650.
Died: 27 August 1692 in Braintree, Suffolk County, Massachusetts  and buried in Hancock Cemetery, Braintree, Suffolk, Massachusetts (now in Quincy, Nofolk County, Massachusetts).
Note: One merged-in profile had the birth date as 28 Mar 1634.
This note was in one merged-in profile: Burials at Hancock Cemetery, Quincy, MA Captain Joseph Baxter, 89th yr May 7 1829 Jerusha Baxter, w/o Joseph, September 20, 1817 John Baxter, 80 yrs, August 30, 1777.'
It may be possible to confirm family relationships with Abigail by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share some percentage of DNA with Abigail: