Are More False DNA Matches Likely In Endogamous Populations? 

This was so helpful! Understanding that endogamy occurs over several generations helped me better see the differences! Thank you!

Just so you know, Ashkenazis didn't only marry one another for religious reasons. It was just as much because there was limited opportunity to "marry out," due to the feelings and attitudes of the surrounding populations. When your choices are restricted for both internal and external reasons, you marry within your group, unless you leave the area. (One of my grandmothers married my non-Jewish grandfather in the U.S., against her family's wishes. Her Europe-born parents came to the U.S. in the 1890s, before she was born, and she grew up and met her future husband here. They married in an Episcopal church in 1921. While intermarriage was unusual in their generation, it wasn't unknown, and it's grown in frequency with each generation. Which shows that opportunity is a big factor.)

Thank you for the endogamy videos! I appreciate them, I have this in my family and it’s so confusing.

My great-great grandmother was from St Keverne, Cornwall. Seems like she may have encountered a Spanish fellow, and had a child with him. Then moved to London, and had another 4 children. None of the birth certificates have a father's name, no evidence she ever married. Census records state she is a widow, despite having more children more than 9 months after. Anyway, I think that my mysterious missing great-great grandfather is also from Cornwall, whom encountered my great-great grandmother in London. I have loads of DNA matches that trace back to Cornwall. Too many to be from one great-great grandparent. I assumed that there was some level of interbreeding, though I can't find evidence of cousin marriages.

Great info thanks for getting me straight. I have collapse!

Québec is an interesting case study of a population that is based on a pretty small initial population that has kept mostly within itself due to religious and cultural reasons. And due to the high quality of church records, our family trees tend to be well documented, very often all the way back to the original settlers

Oops. I premiered this one at 12 am.

It’s bad in my family. I can’t separate matches on ftdna. On one side I come from the center of endogamy in Norway and Sweden. So much so that they have written studies on it. On the other side I come from Hills of Kentucky where 3 families settled, intermarried and didn’t stop for 150 years. When I got that branch back to 1600 Scotland I read “each of the children married their cousins” I closed the webpage and took a break. What can you do but make your tree private and pick a diff hobby. 😳

Appalachian DNA is showing similar patterns to this. As I'm filling out my family tree going back further than I ever knew before, it is obvious of cousins marrying cousins, and an ancestor grandmother or grandfather is the same two, three, or four times over. It made sense when you talked about the low center Morgan's across multiple segments because I wondered how that would have happened. Thanks.

Either I forgot about this video or never went back to listen to it in its entirety before, but cool that you at least covered the part for Polynesians, particularly eastern Polynesians (Hawaiians & NZ Maoris) who are genetically much, much closer compared to western Polynesians, or those in the western part of Polynesia who have been there much longer compared to those in the east.

I think there may be a need to discuss what is a false match. Because you have even stated that you could be related to the person even though they are a false match, which is counter intuitive. You say that there you are not going to find records, which includes all NPE, and many adoptions. And then that would also include anyone who's records were caught in a fire or flood, even if that record is five years ago or 150 years ago. Like I know what it is but something to clarify what would be considered a false match and what isn't. I imagine that there would be a qualification based on possible generations, CM about and maybe how many segments? I don't know. Just what my brain was processing as I was watching the video.

Thanks. It made me chuckle. I probably have Genghis Kahn as a common ancestor with a billion matches! 😉

Both my maternal and paternal ancestors are form northern New Mexico a high endogamy community for hundreds of years. Couple questions how high of cm match should I not be concerned about being a false positive, and if I understood correctly lower cm matches with more segments should be a concern? Thanks in advance for any advice!

You mentioned that Ancestry has done a good job at trying to limit some of the endogomous matches. Why would you want to do that? Wouldn't you want to know about the endogamy in the family? I found out that my Dad was not my Dad through ancestry, .. yes quite a shocker, but the half siblings from that side tried to state that endogmy was giving a false match to a biological dad. I disagreed. After speaking with a professor she stated Endogamy occurs in distant relatives, not a close match such a biological Dad. So back to the question, why would Ancestry want to "limit" the amount of endogoumous matches. I would think it interesting to try and sort it all out.

I’m half Cajun. The amount of overlap in names is alarming 😂 endogamy for sure. It’s so hard to sort it all out

I wish I could see you work with matches where there is endogamy or pedigree collapse. I know there is collapse in my family, rural families and all that. I suspect there was endogamy prior to immigration to America. My cM looks pretty normal, but the segments to bump on the high side.

On MyHeritage, I found an approximately 3rd cousin once removed DNA match has a great grandfather called Jesse Garnett Lee Sr. It is a small world. Jesse might have married my 1st cousin twice removed Mary E Overton.

Andy sir, i have a doubt. How would you differentiate between your true and false genetic matches in 23&me?

I belong to a community that has pedigree collapse and a few hundred years of intermarriage which I believe makes it endogenous. I certainly have matches showing too close to me but actual MRCA is much further back. Have you heard that South Africa is endogamous?

Ancestry DNA is playing around with the landing pages again. When in Unviewed and clicking on View Match, often the layout of the page is different than usual. And it appears they are only showing 10 spaces of the 'note' on the landing page. The may be just experimenting, or not. I guess we'll see.

Question: on Ancestry it show no match with a dna match for Gedmatch that I test at 100 SNP 5cM with all the B36 B37 B38 selected which showed matches from 9 chromosomes matched twice on 12th Chromosomes Chromosome 3 Chromosome 8 Chromosome 10 Chromosome 12 Chromosome 13 Chromosome 16 Chromosome 22 Did that test bySNP 100/ 5cM to get the MRCA generation: at 6.1 Total Half Match segments (HIR) 46.9cM Estimated number of generations to MRCA = 6.1 Largest Segment 7.4cM 8 shared segments but in the tree on FamilySearch where meant to be 12th cousin twice removed where is does show they married cousins and generations before them too is this how it is showing no match on ancestry matches

My husband and I share 4th great grandparents and possibly more. After we had been married about a few years I found out his father and my father came from the same small town near Columbia Mo. and several generations had lived in the area since coming from Virginia. Joe and my son was born with a genetic immunodeficiency similar to bubble boy disease but the doctors wouldn't test for it. Can you find out if this could have been a problem with these current tests? We both were tested through FTDNA and Joe died a few years ago so a new test isn't possible. Our son died when he was 18 in 2002. I know it doesn't really make a difference but just curiosity.

Is having over 200 shared matches with an 8cm match a sign of endogamy? (AncestryDNA)

Question: on Ancestry it show no match, with a dna match on Gedmatch that I test at by 100 SNP 5cM with all the B36 B37 B38 selected which showed segment matches on 8 chromosomes matched twice on 12th Chromosomes Chromosome 3 Chromosome 8 Chromosome 10 Chromosome 12 Chromosome 13 Chromosome 16 Chromosome 22 Did that test bySNP 100/ 5cM to get the MRCA generation: at 6.1 Total Half Match segments (HIR) 46.9cM Estimated number of generations to MRCA = 6.1 Largest Segment 7.4cM 8 shared segments but in the tree on FamilySearch where meant to be 12th cousin twice removed where is does show they married cousins and generations before them too is this how it is showing no match on ancestry matches

So from these Web DNA sites, how many generations back would you say is accurate if there was endogamy? We have a situation where a distant cousin(4-6th cousin) from another island has 2nd cousin cM #s. Does that mean her side must have had endogamy up until recently? What is considered Pedigree Collapse?

It certainly seems like there's endogamy in mine. My maternal Irish ancestors and then on my paternal grandmother's side there were Nova Scotians and colonial New York families that all seemed to intermarry and stay in the same general area for hundreds of years. I have what I assume are a lot of false matches from these colonial ancestors.

I am Eastern European. My mom did a test and my result is phased with hers. But when I open common relatives on 23&me, I get North Americans who seem to match me on both sides. Does it mean that Eastern European immigrants in the USA are all from the same villages/neighbourhoods?

If the match has other matches in common, can we expect that it's not a false match?

~1:10 (while speaking of pedigree collapse) "brothers marrying sisters ..." No, absolutely not. You are repeating one of the worst myths about pedigree collapse. (Unless you are talking about incest, with a man marrying his own sister, and there is no indication that you are speaking of that situation.) A dozen Smith brothers could marry a dozen Jones sisters and there would be ZERO pedigree collapse, because they and all their offspring would each still have the normal number of ancestors. There would be more sharing of ancestors, but only in the same way that siblings share the same ancestor, and no one thinks that causes pedigree collapse. So why would you think that double cousins would cause pedigree collapse? It is ONLY if those cousins marry -- people who are ALREADY related to each other by blood -- that pedigree collapse occurs. Please stop parroting this very false myth.

I’ve never failed to triangulate a match in my Jewish dna matches and I’ve never found the common ancestors OBVIOUSLY. The matches are real the ancestors are lost. With some exceptions I’ve never found non Ashkenazic people matching my Ashkenazic segments as I use Gedmatch so have mapped it out. The same isn’t true for my Sephardic Jewish side I get more diverse matches like Mexicans Iberians and others match me on those.

I like the information but I’m someone who likes to just hear it already and you drag some moments out. Slowww. But good info!

3:22 you say "...much smaller amount of DNA"... And I wonder... the DNA Pool gets smaller and smaller is what you are talking about, correct? We also use the word "gene-pool" It happens not only because the people who moved away did not have all the genes the people left behind did... nor only because some DNA does not get inherited by any of your children... but because not all people have children that grow up to have children themselves.

Andy, great video on Endogamy. I do wonder why you would describe a likely “valid but distant” small DNA matching segment as false? The difficulty in actually finding the MRCA, in my view, shouldn’t lend itself to saying sense we are unable to pinpoint the Ancestor, we will lump this kind of outcome in with false matches that present other indicators regarding why they are false. I’m much more comfortable with saying the match is “likely valid - but also too far back to more specifically identify”. Visual Phasing helps me greatly in making these kinds of calls. Your thoughts. Thanks for all you do! Jerome 11 Jun 2023

My chromosome 6 is Sephardic on HLA it matches so many people including Ashkenazic Jews Spanish and Mexicans and the ancestors are totally lost so it’s a real match but useless probably pre 1492. Non of my Ashkenazic or Sephardic segments are unrelated but they are distant

DNA does not lie. Just because it does not fit in your box does not make it a false match. It is still a match. Endogomy is an irrelevant term because they are gonna still be related. You can just add a code like 2nd-3rd cousin (e)

I don't agree with most of what you've said here! I live in Ontario, Canada, very close to the Quebec border where a lot of my ancestors were after they came from France. My parents are 1C1R, dad's grandmother and mom's father are siblings . That's pedigree collapse, because I don't have 8 distinct separate great grandparents, or 16 distinct separate 2nd great grandparents, or 32 separate and distinct 64 3rd great grandparents because I'm related to them 2 different ways and all of their descendants are related to mom and to dad, 2 different ways on that common line. Onto the endogamy part of my tree. My ancestors, for at least 350 years came from the same small geographical location in Quebec, Canada and they intermarried over and over again and eventually they move west into Ontario. My recent ancestors have been in the same small town for about 175 years. Many have intermarried there, because the lines get blurred over time. I can trace all of my great grandparent's ancestors to the same geographical location and even to the very same parish where most of them were baptized, married or buried their dead. Present day, my tree is a virtual wreath, I'm related to a lot my matches 3-8 different ways (8 is the record so far!) My divorced brother looks to me to ask if that lady he wants to date is related to us! I'm finding out that the kids I went to school with, played with as a child, dated when I was a teen, socialized and worked with as an adult, were neighbours with, are my fairly close cousins, and I never knew this until I started researching 20 years ago. That's endogamy! My son's father is related to me at least 7 different ways, I didn't know this until many years later!

DNA does not lie. This gives people an excuse to exclude people they don't want to accept as being a TRUE relative. I don't agree with this at all. People are always trying to pick and choose who is related to them. This is wrong. My opinion. If the DNA supports a connection you are connected. End of story.

It is not false...it is a cluster of people that YOU have to figure out which ones you came from. Everyone has it at some point. You people saying false are the ones who are false.