Why Doesn't a DNA Match Match Any Other Relatives? | Genetic Genealogy

have you looked at your DNA matches and  you found some that don't share any other   DNA matches in common or at least none that  you know of why could this possibly be? Well   today I want to tackle that question and  I want to go through some of the reasons   why you may have matches that don't match other  people that you know have a common ancestor with   you. Howdy welcome to Family History Fanatics  where we love helping you climb your family   tree and have fun along the way. If you're new  to genetic genealogy chances are you have lots   of questions. Be sure to check out the link in the  description below that contains our free guide to   the five most common DNA questions we are asked.  So the first reason is that this is a false match.   Now false matches typically show up at very low  centimorgans. So seven centimorgans or below   you may have false matches that show up in the 10,  15, 20 centimorgans. And I think I've even done a   video where I showed that there was a false match  at 30 centimorgans. This is really rare. We're   talking of all the thousands of matches there  was like one of mine that was at 30 centimorgans   but false matches can happen. And this is just  because humans share a lot of the same DNA   because when we test with our different companies  they don't divide out which DNA belonged to our   mother and which one belonged to our father.  Sometimes what it's looking at is it's looking   at bits and pieces of both our mother and father's  DNA to create a long enough segment. That's why it   normally happens at these much smaller segment  levels than it does at larger segment levels.   Because it's a lot easier to you know have a  centimorgan or two that is just by chance of   everybody having that. And then take a little bit  from your mom and a little bit from your dad and   then another little bit from your mom and get to  a six centimorgan or a seven centimorgan segment   and it's calling it that. So that's a false match.  Now let me show you an example here of a false   match. In 23andme this is a match that I found  that shares 0.08 percent which is right about 8-9   centimorgans. I believe maybe only 7 centimorgans.  I'd have to do the math but in any case these   are the top matches between me and my match  Adam on 23andme. It's important that you know   not only have I tested both of my parents, but  I have also tested my dad's grandparents. I have   tested all my children. I have tested all my  brothers. I have tested cousins from my dad's   side of the family that have tested first  cousins. And the highest match ends up not being   any of those. None of those family  members show up as a match to this person.   So in this case since I got all of my DNA from  my mom or my dad and neither my mom nor my dad   nor any of the other close relatives on my mom or  dad's side show up this match is a false match.   Again they do happen. You're going to find them  at the much lower levels. And that's why if you   do have family members that have tested it's very  important that you're looking at these shared   match lists to make sure that the matches that  you're looking at. When you get to really below   15 centimorgans make sure that they're really  true matches. So reason number two is that you   may have matches that don't show any of the known  common ancestors or known matches that you have   to do with minimum matching criteria. There's  lots of different ways that this can happen   this can happen with what centimorgan level.  They say that a match actually is whether it's   six or seven or eight centimorgans. As you are  testing with different companies the different   algorithms are going to call a segment a different  size. So you may have something that for your test   shows up as seven centimorgans or eight  centimorgans which is above that threshold   but because your mom or your dad tested with a  different company the company calls that exact   same segment six centimorgans as opposed to eight  centimorgans and six centimorgans is below their   threshold. So your mom or your dad doesn't show  up in that match list but you show up as matching   this person. Another way also is with ancestry  they only show your shared matches that are above   20 centimorgans. So there's lots of different  ways that this minimum matching criteria might   take some of your close relatives out of  that match algorithm this is me and dh.   And dh matches me at 20 centimorgans. And you'll  notice here that he matches Phil who happens to be   me also. And the next match is somebody from  my extended family that I don't match except   about 140 centimorgans. So my mom, my dad,  none of my siblings, my aunts, and uncles,   none of these people are in here that I would  expect in here. What this is when I went and   searched for it is this person actually matches  my mom at 19 centimorgans. So it is below the 20   centimorgan match that that ancestor uses for  this. So it doesn't show up on my shared match   list. So this is a case of our minimum matching  criteria removing matches that really are there   but it looks like. Now that they aren't there  reason. There is this is a unique DNA segment.   If you have not had your mom and your dad test,  also what you might find is that you have several   other close relatives that this match doesn't  match. In this case what you match with that   person is a unique segment that you've had  passed down. To you that wasn't passed down   to any of your other relatives. In other  words either your mom or your dad received it   but none of the other relatives received it.  You're not going to know this unless you have   your mom and your dad have tested. So that  is a possibility also and again this is   usually we're talking about a small segment  somewhere in the 7 to 10 centimorgan range   because once you start to get to much larger  segments there's much greater probability that   a piece of that was also shared with one  of your other relatives that you've found.   Now there are you know obviously a couple  of other reasons that I didn't cover here.   Basically if you know family members haven't  tested. There's very few family members and   there might be that you have some matches that  just don't show up. But those I think are the   three main reasons that you should investigate and  try to figure out whether or not it is with. The   first two you need to have had your bomb and your  dab test. And with the third one your mom and your   dad couldn't have tested in order for that to  be a unique segment. If you have questions about   why some matches aren't showing up you can put  it in the comments below and I'll try to answer   it. Now if you'd like to learn more about  false segments you can watch this video up   here. But if you want to learn something else  about DNA then watch this video down below.

Channel: Family History Fanatics

Views: 3,475

Rating: 5 out of 5

Keywords: false DNA matches, DNA Match Doesn't Match Any Other Relatives, dna matches explained, false dna matches, ancestry dna false matches, false positive dna matches, are dna matches ever wrong, why false dna matches is, what false dna matches is, genetic genealogy, dna matches, dna test results, genetic genealogy for beginners, dna results, shared matches, family history fanatics, improved dna matches, understanding dna matches

Id: UkDtca20dUs

Length: 7min 47sec (467 seconds)

Published: Wed Sep 08 2021