DNA from Morris County, New Jersey: 23andMe

From my Morris County, New Jersey ancestors, some cousins appear in the DNA databases.

My father's third cousin from this branch has tested his DNA.  We can see the shared segments of autosomal DNA shared with my father, his siblings, and this third cousin.  The common ancestors were Calvin Cook (1827 - 1889) and Mary Neal (1829 - 1898) of Morris County.

By viewing where the DNA is shared, we can find other, more distant cousins who also share DNA in these same spots.

For this discussion, we focus on the shared segments on chromosome 12 at 23andMe.  Two of my father's siblings share DNA on chromosome 12 with the third cousin.

A few people ("DNA cousins") also share these same segments with the relatives on my end- my uncle and our third cousin.  One of them has a family tree and responded to my inquiry.  She shares an identical segment of DNA with two of my uncles and third cousin.

We need to triangulate the match.  Two full siblings count as one point of the triangle, as their ancestors are identical.  We do not have to search our entire family tree to find the Most Recent Common Ancestor.  We look instead at the set of ancestors common to the third cousins:  Calvin Cook and Mary Neal.

Mary Neal is a tail end in my family tree.  Her ancestry is unknown to me at this time.  Only Calvin Cook's tree is available.  If the segment came from Mary Neal, we could possibly break through that brick wall.

One of two branches that may hold the Most Recent Common Ancestor
of the DNA cousin.

When asked for ancestors that were in northern New Jersey in the 1800s, the DNA cousin provided the couple Peter Vanderhoof (1797-1847) and Rachel Peer (1800-1850).  After time, research, and correspondence, the Most Recent Common Ancestors were identified as Jacob Vanderhoof (1772-1847) and Ann Hopler (1772-1841).  They were the parents of Peter Vanderhoof, the direct ancestor of the DNA match, and they were the parents of Elizabeth Vanderhoof (1799-1878), the mother of Calvin Cook, in my direct line.

This makes this DNA cousin a Fifth Cousin to my father, his siblings, and their third cousin.

Elizabeth Vanderhoof (1799-1878) is buried with her husband, Stephen Cook (1797-1843), in the Cook Cemetery in Denville, Morris County, New Jersey.  (Now enclosed by a golf course.)

Peter Vanderhoof and his wife, Rachel Peer, are buried in the DeMouth Family Burial Ground (front yard of a house) in Denville, along with Peter and Elizabeth's parents, Jacob Vanderhoof and Ann Hopler.  (Ann Hopler's mother was Elizabeth DeMouth.)

But there could be other ancestors in common.

Jane Peer was the 5th great grandmother of my father.  She married John Cook (1745-1821).  She was probably born around 1750 and died before her father, Samuel Peer, died in 1818.

Rachel Peer (1800-1850) was the 3rd great grandmother of the DNA cousin.  Rachel's place in the Peer family of Morris County has not been determined.  Rachel Peer and Jane Peer, like the other Morris County lines, were probably related.  The shared DNA could be from Peer and not Vanderhoof and Hopler.