Large Amount of Shared DNA with 6th cousin?

[Giusvalla]

Can anyone explain this match that my mother, my son and I all share with a particular individual "Theresa"

My Mother's Match to "Theresa"
Total Shared cMs: 95.6
Total Shared Segments: 4
Largest Segment: 73.4

My Match to "Theresa"
Total Shared cMs: 132.6
Total Shared Segments: 6
Largest Segment: 87.3

My Son's Match to "Theresa"
Total Shared cMs: 100.1
Total Shared Segments: 2
Largest Segment: 87.9

I'll point out that my father does not match this individual, even at the lowest cM thresholds.

My full sister also does not match this individual.

My wife also does not match this individual.

Going by what the shared DNA suggests, it appears to me that "Theresa" would be quite closely related to us, possibly a 2nd cousin. Our genealogy paper trails indicate, however, that "Theresa" is my mother's 6th cousin, and then again more distantly through at least two or three other early New England ancestors. We both share a significant amount of ancestry in the area of Wells, Maine, including the common ancestors previously described.

Can anyone provide some reasons my mother, son and I would share such a large amount of DNA with our 6th (etc.) cousin "Theresa?"

Why do I share so much more DNA with "Theresa" than my mother? Even my son shares more DNA with "Theresa" that my mother.

And why does my full-sister not match "Theresa" at all?

This one has me scratching my head. What's going on here?

Thanks for your help!

[prairielad]

Are these FTDNA amounts?
are any of your tests transfers to FTDNA, if so which company and when did you test?

[Giusvalla]

Are these FTDNA amounts?
are any of your tests transfers to FTDNA, if so which company and when did you test?

These are raw DNA results transferred from Ancestry to MyHeritage.

[ltd-jean-pull]

I suggest you compare the kits on a site that has a chromosome browser - FamilyTreeDNA and/or Gedmatch.

[Giusvalla]

Unfortunately I do not have access to the raw data for "Theresa."

Is there any significance to the rather large "largest segment" in relation to the few shared segments? My son, for example, shares only 2 segments (total of 100.1 cms) with "Theresa," but the largest of the 2 segments is a whopping 87.9 cms.

Are we possibly looking at the result of shared ancestry among an endogamous population? Our respective families lived in Wells, Maine from the earliest settlement (1640s) until the present, and we share several ancestors, but none closer than the 6th cousin range. Any thoughts on this?

Thank you again.

[MMaddi]

Unfortunately I do not have access to the raw data for "Theresa."

Is there any significance to the rather large "largest segment" in relation to the few shared segments? My son, for example, shares only 2 segments (total of 100.1 cms) with "Theresa," but the largest of the 2 segments is a whopping 87.9 cms.

Are we possibly looking at the result of shared ancestry among an endogamous population? Our respective families lived in Wells, Maine from the earliest settlement (1640s) until the present, and we share several ancestors, but none closer than the 6th cousin range. Any thoughts on this?

Thank you again.

If you have ancestry from pre-1650 New England, you are in an endogamous community. It's a classic example, along with Ashenazi Jews and French-Canadians.

The population of the early British settlers was small. This meant that mid to distant cousins were marrying each other over several generations. There may have even been cases of 1st and 2nd cousins marrying.

This means that everyone who shares this ancestry with you is a distant cousin. It would not just be in one line. You and your match share common ancestry in multiple lines, which contributes to the large segments that have remained and you share.

This is probably at least part of the explanation for the large amount of DNA you share with the match.