Updated 26 Jul 2020:

Current data related to connections with William Cecil, Lord Burghley's extended family can be found at: 

https://sites.google.com/view/lord-burghley-families/home

Updated 29 May 2018:

BigY testing results are helping define the overall structure of the various family connections back to medieval times. The currently defined structure of the family is as follows:

Around 1062 in SW England near theWelsh border an original common male ancestor was born. This was before the family had adopted surnames and we do not know his name. The DNA results showus however, that his male descendants created several family branches in the time before surnames were finally adopted.

One of those branches was started by a male born about 1275. His descendants formed at least three separate branches. One of those branches was that of John Cecill (Cissell) who arrivedin St. Mary’s County, Maryland in 1658. ; Another resulted in a male born about1345 and from which there are at least two known lines: That of William Cecil,Lord Burghley (Treasurer of England and Secretary of State for the first QueenElizabeth) and the Cecil family who arrived in Prince George’s County Maryland in the later part of the 1600’s.

The original ancestor from about1062 also had a descendant born about 1315. Several of his descendants adopted their own surnames. These included Gilbert, Harris, Howells, Word, and Webb.

Using more BigY tests and some initial whole genome sequencing tests, we are trying to better define some of the more recent connections between the descendants of John Cecill (died in St. Mary’s County, Maryland in1698). We are also trying to determine in more detail the connections between the Gilbert, Harris, Howells, Word, and Webb branches of the family.