This sounds like one of those numerous cases where a line on the net [i believe from Ancestry c1998 and
thence to Family Search] has been copied to other sites and become 'fact'. I dont know if this the line
referred to, but just about every Holland in the USA seems to have adopted it.
Because its so common it may be worth a moment to examine.
The real Henry Holland Duke of Exeter [1430-75] married c1447 Anne of York [1439-76] sister of Edward IV
who later married Thomas St.Leger [1440-83] She had 2 daughters, 1 by each husband.
The eldest, Anne Holland [1461-74] m Thomas Grey [1455-1501] eldest son of Elizabeth Woodville, but she
died childless as Todd says. According to wiki, the younger Anne St.Leger [1476-1526] was allowed to
inherit her mothers 'Holland lands' when she married George Manners [1470-1513] in 1490.
However in the fictitious line Henry Holland is also given 2 sons, Henry and Thomas.
1 Thomas Holland [1461-1501]
2 Henry Holland [1490-1561] m Anne 'Plantagenet' dau of Edward IV and Katherine Woodville
3 Henry Holland [1527-70] m 30/1/1547 Hillary Barwarde [1527-61]
4 John Philemon Holland [1556-1628] m 5/3/1584 Mary Mollinax
5 Gabriel Holland [1596-1665]
no1 As Todd says the Duke had no male heir so any Thomas was not his son. There are other Thomas Hollands
in this period but they are not his son. Findagrave has a record of a Thomas Holland buried 29/7/1540 at
St.margarets Westminster [next to the abbey], but i havnt seen the source for this or any connection with
the Exeter family.
no2 There doesnt seem any proof for this person and he did not marry Anne of York [1475-1511]; she married Thomas Howard. As he is sometimes called Duke of Exeter on Family Search et al this seems a conflation of
Duke Henry who died 1475 and no3.
no3; The records for this marriage again come from St.margarets Westminster, and a Henry Holland born 1527
was buried in st.margarets according to findagrave but i havnt seen the source for this or for his
marriage or anything to connect him with the family of the duke of exeter. I have seen some digital images
of the parish registers connected to these records, but these relate to the 1650s.
no4; a John Holland did marry in 1584 in westminster but there seems no proven connection with either of
the other generations or with other dates associated with him.
no5; existed but i think his dates have been confused with another man who emigrated and died in Virginia
in 1637 with others who died later in 1660 1665 or 1670. Its not clear that he is the same who was born in
1595 or 96.
Holland seems a very common name and there may be a connection with this Westminster family or another
Holland family but not a descent from Henry Duke of Exeter.
There is a useful discussion about this line on Wikitree which addresses these and the USA links
https://www.wikitree.com/wiki/Holland-645
About the DNA; how do they decide from a test result that it shows you are related to some bod 500 years
ago? Is there a DNA bank somewhere which holds test results of known descendants to compare with?
Mike