DeJean Cousins in America

NOTE: Since this family group uses the same batch of names in several generations, with multiple same-named men in each generation, I will identify each man for the first time by his Christian name and birth year, then refer to them as their namebirthyear altogether as one.

In my article for Stephen DeJean, I mentioned having found another family of DeJean’s in New York who arrived near the same time and Stephen, his parents, and siblings. I came across a bulletin query from a man, we’ll call him GD to respect his privacy. His query was very interesting to me because of the names, locations, and time frame of his DeJean family.  

My name is [GD]. I posted a thread last week on this site and did not get a response. I’m really not sure that it went through so I will repeat I am descended from Stephen Louis DeJean or Count DeJean < 1743 > France. Descendency is through his son Dominic < 1769 > France –Louis DeJanes < 1791 > France–Edward DeJaynes b. 1816 KY.–James Robert DeJaynes b. 1860 IL.–Floyd Andrew DeJaynes to my father. Can anyone give any info. about the lives of any of these ancestors? Has anyone gone further back to the French records? Thanks for any help.

DeJean discussion board (Ancestry.com), DeJean Family thread posted 5 June 2006

I had a few small problems with this lineage. Stephen did not have a son named Dominic. But he did have a brother named Dominic. Stephen was not born in 1743. By my calculation, he was born between 1778 and 1782 (we’ll say 1780 for ease). Additionally, his brother, Dominic, was born between 1780 and 1790 by my calculations (we’ll say 1785 for ease).

Well, various genealogists routinely name Stephen1780’s father as Count or Conte Stephen Louis DeJean – with absolutely no evidence.  The error is perpetuated by public trees, linking to other public trees, ad nauseam. There really is no hope in correcting this on Ancestry.com or FamilySearch.org. I’ve tried.

So, I pulled the string. Floyd Andrew DeJaynes can be confirmed to descend from Louis DeJanes b. 1791, husband of Elizabeth. Louis1791 being the son of Dominic1769 is unconfirmed, though I have no reason to believe GD doesn’t have some kind of evidence. The fact that I can independently corroborate GDs lineage to Louis1791 leads me to believe that GD must have evidence.

Because I could not easily make it past Louis1791, I could not establish if there was a familial connection between him and Stephen1780. Further, the birth year of 1769 for Dominic, makes him of the generation for Stephen1780’s father. And since I am confident in naming Stephen1780’s father as Lewis b. 1757 (Louis1757), I am certain Dominic1769 is not Stephen1780’s father. Lastly, the facts surrounding Louis1791 do not match any of Stephen1780’s brothers. Who were these other DeJeans?

DNA to the rescue?

The question mark is because while DNA is good – it’s not exact or without error the further back we go (the smaller the cM or centimorgan).

Here is where articulation becomes tricky.  Note, I am changing the names of my matches for their privacy as I have not sought permission to use their names or profile IDs. Enter DNA match “Beta”. I was sorting out my uncategorized DNA matches on Ancestry by targeting known DNA matches and checking their “matches in common”. When I check Beta’s matches in common, several other uncategorized matches appear. This means, while Ancestry’s algorithms haven’t been able to determine how these matches are connected, I can still narrow down what line they should match through. If you do this methodically, you can “filter” out other possible family lines.

“Delta” is one of hundreds of distant cousin matches to Uncle M that do not show up in any of our Thrulines on Ancestry.com. But, Delta appeared as a match in common with Beta, and Beta appears in Thrulines as a direct descendant of Stephen1780’s brother, Dominic1785 (I did not find errors or inconsistencies with Beta’s research). The triangulation between the three matches isolates our matches in common specifically to siblings and cousins of Stephen1780. As luck would have it, Delta has published his tree and had the surname “DeJaynes” in it. Intriguing.

I have independently confirmed Delta’s lineage up to a man named Nester Enoch DeJanes b. 1810 in New York, d. 1896 in Pike County, Illinois. Pike County rang a very loud bell because when I had pulled the string on GD’s published line, I tracked descendants of Louis1791 to Pike County, Illinois. And now I have brought you full circle, folks.

Delta likely descends from the same line that GD claims (though they are not the same people).

Still, it’s an unconfirmed theory (or perhaps I am being too doubtful). Nestor Enoch DeJanes can’t be easily confirmed as a son of Louis1791. I only suspect he is a son because of geographic proximity. Nestor’s proposed brothers, who can be confirmed as sons of Louis1791, are all found in Pike County, Illinois in the same years, were all born in New York, and many have reported their father’s birth as France. But they are 10+ years younger than him and I haven’t found any possible siblings to fill that 10-year gap.

A professional DNA analyst would say that it’s a “good” chance that the DNA connection is reasonable. Beta’s match to Uncle M is 23cM. Delta’s match to Uncle M is 22cM. Professional DNA analysts cite a lowest accurate threshold of 10cM. At these generations and cM numbers we are pushing the accuracy limits of autosomal DNA. Ok, ok, geeky science stuff.  

Now, if you are just starting to, or thinking of, dabbling in DNA, let this geeky talk be a lesson learned that Ancestry’s commercials are misleading – DNA genealogy breakthroughs aren’t that quick and easy for the lay person. It requires a lot of study and understanding for how DNA matching actually works. Seriously, I might as well go back to college to get a degree in genetics.

Regardless…the signs are multiplying, indicating that Stephen DeJean may not have arrived in the United States with just his parents and siblings, but also with first cousins. Perhaps there are others…