A Second Cousin Adds to My Chromosome Map and Answers A Nagging Genealogical Question

I was so happy to receive results for a 23andMe kit that I had sent to my second cousin a few weeks ago. I haven't had much opportunity to work on my own research or add to my known cousin studies lately, so it was nice to get a result that not only put to rest a nagging doubt about my genealogy, but gave me a substantial amount of DNA to add to my chromosome map.

Willard and Blanche (Purdy) Moore

These new results were from a male second cousin of mine. Our common ancestors are our great grandparents Willard Moore and Blanche Purdy. Having him test killed two birds with one stone, so to speak. He is related to me on my father's direct paternal line, so he carries the Moore surname. Since my dad has so few Y-DNA matches and only one borderline 33/37 Moore surname match, I have been wanting to "walk up" my Moore ancestral line, testing as I go to make sure that my all of my dad's relatives match as they should.

Through DNA testing, I have already confirmed that my dad and his brother were full siblings, as expected. The nagging doubt sprung from the fact that when I compared the 23andMe results for my female Moore second cousin, we shared much less DNA than expected for that relationship (1.17% versus 3.125%). That held true for comparisons against all of my relatives except for my paternal aunt, so I was looking forward to these new results to confirm that our Moore grandfathers were really full siblings.

Jack and Fred Moore

When I chose who to test with this kit, I looked for someone who was not only related on this line, but carried the Moore surname, so I could confirm that he shared the same usual I2b1 Y-DNA haplogroup subclade as my father. My Moore Cousin #2 fit the bill perfectly.

Fred and Jack with their father Willard

Today I received his results and not only does he carry a Y-chromosome with the I2b1 haplogroup, but he shares 3.84% of my autosomal DNA over 9 segments. Much of this was shared on different segments than my female second cousin on this line (they are first cousins), so it will really enhance my chromosome map. In the chart below, you can see the first Moore 2nd cousin that I compared myself to in the dark blue and the latest one in the light green.

I was surprised how different the DNA is that we share since they are (confirmed) first cousins. Notable is the huge 90 cM segment on Chromosome 2. I have a much smaller segment in common with Cousin #1 on that chromosome, so this new comparison will help to extend that segment to cover a significant amount of my paternal chromosome 2 in addition to adding a smaller segment toward the end of the chromosome.

This was a good reminder of how much autosomal DNA sharing can vary within the acceptable range for a relationship. This concept can also be demonstrated by comparing my sisters and myself against this male Moore second cousin. The amount of DNA that I share with him (in light blue) is approaching double what one of my sisters (in dark blue) shares with him.

Another interesting aspect of this comparison is that I now have a 2nd cousin, a 3rd cousin and a 3rd cousin once removed to compare from this Moore line.

Notice how quickly the amount of DNA shared drops from one level of relationship to another, especially the dramatic drop between 2nd and 3rd cousin. Of course, this is just an example and not necessarily indicative of the expected amount of sharing for these relationships.

Probably the best thing about testing this cousin is that I get to update my chromosome map!

My Chromosomes Mapped to My Ancestors (click to enlarge)

This result really inspires me to send those other kits that I have sitting on my desk out to additional cousins! So, who's next?

Known Relative Studies at 23andMe: Second Cousin Comparisons, Allen Great Grandparents

I am very pleased to report that I have received the results for my Allen second cousin's DNA test. This is exciting because he shares the only set of great grandparents from whom I have had no genetic data up to this point. Our common ancestors are our great grandparents George Henry Allen (1880-1965) and Fredrikka Herstad Allen (1871-1953). They were both immigrants to the United States around the turn of the 20th Century. George was from Australia and Fredrikka was from Norway. They met in San Francisco and married shortly after the Great Quake of 1906. I descend on my paternal side through their daughter Wanda and this cousin descends maternally through their daughter Flora.

I was surprised to see how much DNA we all share with our Allen Cousin. My family shares more DNA with him, across the board, than we have with any of the other cousins in my "Second Cousin Studies". My sisters and I share well above the expected percentage for a second cousin of 3.125% of DNA in common with our Allen Cousin: 4.45%, 4.27% and 3.64%.

Three sisters compared to their second cousin

As usual, you can see the unique pattern of inheritance, with each sister sharing different portions of their genome with this cousin (shared DNA with each illustrated by the three different colors).  You an click on the chart to get a closer look. Chromosome #6 is especially interesting because we all share a majority of that chromosome with our cousin, meaning that for all three of us siblings the Chromosome #6 that we inherited from our father was inherited almost exclusively from his mother Wanda and, in turn, his Allen grandparents.  At the same time, we can be confident that our Allen cousin inherited his maternal Chromosome #6 almost entirely from his grandmother Flora and her parents George and Fredrikka. In my experience, it is a bit unusual to see such a large portion of DNA inherited intact over multiple generations such as this, especially by all tested descendants. Conversely, you can see that none of us have inherited any common DNA on Chromosomes #4, 5, 8, 10, 11, 15, 21, 22 or X. That doesn't mean that we didn't inherit any DNA from our Allen great grandparents on those chromosomes, only that we cannot detect any in this comparison due to the lack of shared DNA in those areas. In order to be able to detect the common ancestors' DNA, BOTH sides must inherit the same genetic blocks. If we tested this cousin's siblings, we would, almost certainly, be able to pinpoint more DNA from the Allens in myself and in my close family members.

Next I compared our Allen Cousin against three of his second cousins once removed, children of the sisters in the first chart.

Allen Cousin compared to three 2nd cousins once removed

As you can see they retained much of the common DNA on Chromosome #6, but lost many of the other blocks of DNA that their mothers had in common with the Allen Cousin in the first chart. Overall, they were still on the high sharing side with 2.29%, 2.02% and 1.81% instead of the expected average percentage of 1.563% between second cousins once removed. Below is a closer look at the autosomal DNA inheritance pattern of one of the sisters and her offspring compared to our Allen Cousin.

Our Allen Cousin compared to one sister and her offspring

You can see that most of the DNA in common was retained on Chromosomes #2, 6, 13 and 17, while much was lost on Chromosomes #3, 9, 12, 16 and 18.

Lastly, I compared my aunt and uncle to this cousin. Although they are first cousins once removed, they share so much DNA with him that they would appear to be full first cousins. In fact, that is what 23andMe predicted their relationship to be with 11.8% and 11.1% of their DNA in common. Since first cousins are expected to share an average of 12.5% of their DNA and first cousins once removed are only expected to share approximately 6.25% of their DNA, you can clearly see why 23andMe's software reached this erroneous conclusion.

The chart below illustrates my cousin's DNA in common with my uncle, my aunt and myself.

Allen Cousin compared to two 1st cousins once removed and a 2nd cousin

In contrast to my sisters and I, who are one generation further removed, my aunt and uncle share DNA on almost every chromosome with him. Since I do not have my deceased father's DNA sample at 23andMe, I added myself to the chart to demonstrate the different inheritance patterns of each of the siblings. The areas where I alone share with him (light blue) shows that my father inherited those sections in common with our Allen Cousin, and his siblings did not (dark blue and light green). For instance on Chromosome #3, my father inherited a longer stretch of DNA in common with his Allen Cousin than his siblings did. On the other hand, my father's sister inherited stretches of DNA in common with our cousin on Chromosomes #4 and #22 that we did not. Look again at Chromosome #6. It is interesting to see that my father's siblings also inherited large blocks of DNA in common with our cousin on that chromosomes, however they are not the exact same blocks that my father inherited, which can be seen clearly in the earlier chart from the three sisters' inheritance. My aunt did not inherit the same DNA as her cousin in the center part of her Chromosome #6, while her brothers did.

I love being able to actually "see" DNA from my Allen great grandparents.

George and Fredrikka Allen

Now that I have second cousins from all of my ancestral lines, my next step is to combine the data from each of my second cousin studies to begin to map out my great grandparent's DNA on my chromosomes and those of my close family. Isn't that exciting?

Identifying DNA from Great Grandparents Using Second Cousin Comparisons

My recent visit to my great grandparents' San Francisco homes inspired me to contact my second cousin from that line and ask him to donate some DNA to my series on second cousin studies. To my great pleasure, he readily agreed with no persuasion necessary. Happily, this is a case of someone who isn't the slightest bit concerned about the implications of DNA testing.

I just received an email that his sample was received by 23andMe. This is very exciting because it means that I will now have tested second cousins from all of my ancestral lines and I will be able to identify DNA from each of my four great-grandparent couples in myself and my immediate family. To me that is very meaningful. Those of us who study genealogy have spent countless hours searching for tidbits about our ancestors, attempting to know them better. It is gratifying to not only know they are a part of us, but to be able to specifically see evidence of this inside ourselves.

For example, in Part One of my series on second cousins, I found DNA from great-grandfather Matti Wiita Reini (specific to one great-grandparents since it was a 2nd cousin once removed relationship). Part Two revealed DNA from Daniel and Millie (Travis) Proctor and Part Three showed DNA from Willard and Blanche (Purdy) Moore. Part Four, yet to be written, will reveal DNA from George and Fredrikka (Herstad) Allen.

My plan is to map the DNA from each of these ancestors to the specific spots on my chromosomes that match each of my second cousins. This then tells me specifically which parts of my DNA come from which great-grandparents. In doing so, I hope to answer the question that I was asked last week at my presentation on autosomal DNA testing for genealogy, "So what does all this DNA matching really mean?" and to inspire more genealogists to explore DNA testing for genealogical purposes by demonstrating to them just how meaningful it can be.


[Update: Here is a rough chart of my chromosome map so far.]

The start of my Chromosome Map of the DNA inherited from my great grandparents above and adding in some data from third cousins below (Click to enlarge)

Known Relative Studies with 23andMe: Second Cousins or Half Second Cousins? (2nd Cousins, Part Three)

In the first two installments of my second cousin studies, I have focused on my maternal side. This time I am focusing on a second cousin from my paternal side. Our shared ancestors are our great grandparents Willard Moore (1877-1934) and Blanche (Purdy) Moore (1888-1935) from Washington State. I am descended from their first son Fred and this cousin is descended from their second son Jack. I don't have as many family members tested on that side, so I have less comparisons to share, however this study brings up some interesting questions.

Fortunately, I have both of my sisters tested at 23andMe. The amount of shared DNA between us and our paternal cousin (PCousin) are 1.15%, 1.87% and 2.4% (in order of our testing). Since the expected percentage of DNA sharing is 3.125% on average with a second cousin and 1.563% with a half second cousin, I was beginning to wonder if we were really full second cousins, sharing both of our great grandparents. However, as my sisters' results came in the percentages were higher and higher. I think it is very interesting that this second cousin shares twice as much with the third sister tested as the first. The percentages are still a bit lower than expected, so more comparisons are needed to determine the exact relationship.

Notice also our paternal cousin shares on only two small places with all three of us. The other blocks of shared DNA are all randomly distributed.

Click to enlarge chart

Since I have tested both of my father's siblings, I am also able to compare them to this cousin. Their relationship is first cousins once removed with an expected percentage of DNA sharing of 6.25% on average. When my uncle's results came in, the match was only 3.33%, again consistent with a half cousin relationship. Then, against the trend, my aunt's results showed sharing of 6.68%, slightly over the expected percentage for a full first cousin once removed relationship and double that of her brother. This was a bit of a relief, but still does leave some question in my mind about whether, in reality, we share both of our great grandparents or only one. I am attempting to get a male Moore cousin descended from my grandfather's brother to test to make sure that he shares my father's and uncle's unusual Y-DNA haplogroup of I2b1.

To more clearly demonstrate the randomness of autosomal DNA inheritance, I compared this paternal cousin to each of the second cousins and their offspring. The second cousins once removed are expected to share 1.563% of their DNA on average, but, in reality, they share 1.26%, .92% and .33%. When you see this, you can begin to understand why at the next step, the third cousin level,  approximately ten percent of the time there is not enough shared DNA to detect a familial relationship.

Look at the chart comparing Second Cousin #1 and her offspring to PCousin. Do you see something that doesn't make sense?

The surprising thing is that the offspring (2nd cousin1xR #1) of the sister (2nd cousin #1) who shared the least with our paternal cousin, shared the most DNA of the three second cousins once removed. In fact, she shares more than her mother does (95 cMs vs 86 cMs) and appears to share an additional segment on Chromosome 22 with our paternal cousin that her mother does not share. Since there is definitely not any shared ancestry on 2nd cousin 1xR #1's father's side with this cousin and I cannot compare my deceased father to see if the match shows up in him, I looked at the both of her aunts to try to determine if they also shared this segment with PCousin and for some reason it just isn't showing up. 

Comparing Second Cousin1xR #1 with her aunt (Sister #2)

Sure enough, there it is on Sister #2's chart. This shows that for some unknown reason, the match did not show up in Sister #1's chart, but it must be there. Perhaps a no-call is breaking the segment into two, thus making it appear to be too small to be of significance.

[**Update - Dr. Ann Turner emailed me about this scenario writing, "...no-calls are treated as if they match, so that's not an explanation. It could be a miscall or a 'fuzzy boundary,' where the child has inherited enough alleles from the other parent to make it appear that the long consecutive run of SNPs is continuing."  She asked if I have access to the raw data for this cousin (which I do not) and further suggested, "If so, you could run David Pike's utility http://www.math.mun.ca/~dapike/FF23utils/pair-comp.php with more liberal parameters." This explanation had occurred to me, but the fact that the match was over 10cMs and appeared in both individuals of different generations led me to believe that was not a possibility. I will update if I learn anything further.]

Regardless, it is exciting to know that these shared segments come from one or both of our shared great grandparents. This realization certainly makes me feel closer to my ancestors that I have invested so much time trying to get to know through my family history research.

Willard and Blanche Moore - It's their DNA! 

Known Relative Studies with 23andMe: More Second Cousin Comparisons

Since my last post on second cousin comparisons at 23andMe was so popular, I have decided to expand on it. Another second cousin of mine recently tested at 23andMe. As a result, I have many more relevant comparisons to share with my readers. This cousin is also from my mother's family, but not on her Finnish side. Our common ancestral couple is Daniel Hewitt and Amelia (Travis) Proctor, my great grandparents. Daniel was born in 1866 in Equality, Illinois and Amelia "Millie" was born in 1870 in Sidney, Iowa.

Again, this is a great example of the random nature of autosomal DNA inheritance. My two sisters share 2.56% and 2.98% of their DNA with our Proctor second cousin, while I only share 1.07% of my DNA with this cousin. (The expected percentage of shared DNA with a second cousin would be an average of 3.125%.) Our unique patterns of inheritance can be clearly seen in the chart below. The long gray bars are representative of the 23 chromosomes and the shorter colored blocks signify the shared DNA between each person tested and our Proctor cousin. (For example, toward the end of Chromosome 1, Sister #1 and Sister #3 share the same small stretch of DNA with our Proctor cousin, but Sister #2 does not share any DNA with this cousin until Chromosome 5.)

Click on chart to enlarge

You can really see here that we inherited very diverse blocks of our Proctor great grandparents' DNA. One of  my sisters inherited almost two and a half times more of this "Proctor" DNA than I did, while my other sister inherited nearly three times more than I did. In fact, 23andMe predicts that we are only third cousins, but correctly predicts both of my sisters' relationships to this second cousin.

From this comparison, it would appear that my sisters ended up with significantly more DNA from our Proctor great grandparents than I did. However, since this chart really just illuminates the shared Proctor DNA with this particular cousin, it could be that my sisters happened to inherit much of the same DNA from Dan and Millie that our cousin did and I inherited almost entirely different blocks. To be sure, I would need to test more cousins descended from these ancestors to see if my comparatively low percentage of sharing continues.

This chart shows how my mother compares to her Proctor first cousin once removed (4.56%) and the DNA inheritance patterns of two of us daughters. You can see that the DNA was passed on quite differently to each with only three small areas of overlap between all three.

The chart below shows that my mother's sister inherited significantly more DNA in common with their Proctor first cousin once removed than my mother did: 4.56% vs. 8.55%.

Based on this, it isn't surprising that my aunt's two daughters in the chart below share much more DNA with this cousin than my sisters and I do (#1 = 4.49% and #2 = 4.69%) and with much larger areas of overlap between the three.

It is always interesting to me to see the inheritance pattern as the DNA is passed through the generations. The following charts demonstrate this with each comparing three successive generations to our Proctor cousin.

Lastly, the third generations in the charts above are second cousins once removed from this Proctor cousin. In the charts below, you can see, once again, that the amounts of common DNA inherited at this level of cousinship vary widely with very little overlap. (The only difference between the following two charts is the dark blue comparisons.)

The percentages of DNA in common for the second cousins once removed in this study were 2.91%, 1.22%, .76% and .33% (expected average = 1.563%). For second cousins, the percentages were 4.69%, 4.49%, 2.98%, 2.56% and 1.07% (expected average = 3.125%).

Dan and Millie Proctor (it's their DNA!)

One Year Anniversary of "Your Genetic Genealogist"

I can hardly believe that it has been one year already since I started blogging about my favorite subject - personal genomics. I could never have guessed how fulfilling and exciting it would be. During this time, this blog has logged 38,591 page views from 102 countries. 23andMe is, obviously, a very popular subject since my most frequented post was about 23andMe's last sale with 8,866 page views (the vast majority of these in only 36 hours).  It is encouraging to see that my recent post on second cousin comparisons from my series "Known Relative Studies with 23andMe" is already in the top ten even though I wrote it less than two weeks ago. (Since slightly over 20% of my visitors come from Google, many of my posts continue to be read long after their publication.) I will be writing a lot more installments for this series, so it is good to see that it is well-received.

 Most Popular Posts over 12 months- click to enlarge

I haven't been able to write as much as I originally intended nor as much as I would like.  Hopefully, that will change in the second year of "Your Genetic Genealogist". I am confident that there are a lot of exciting discoveries in store for all of us and I look forward to sharing them with you.

Known Relative Studies with 23andMe: Second Cousins

I recently received the results for my mother's second cousin. Our common ancestral couple is Matti Yrjanasson Syrjala Wiita (1852-1931) and Justiina Johanssdotter Wiita (1843-1907), both born in Ylistaro, Finland. He descends through their daughter Josefina and my mother and I descend through their son Matti.

I am fortunate to have a number of relatives with whom to compare this cousin. The expected percentage of DNA in common with a known second cousin is 3.125%. He and my mother share 3.27%, while he shares about 3.1% with her sister and 2.77% with their first cousin V.  It is interesting to see in the chart below that each of them inherited mostly unique segments with only a few segments in common. The chart compares my mother in dark blue, my maternal aunt in light green and their first cousin V in light blue to their second cousin (KnownC). All three women have the same familial relationship to him, but due to the random inheritance of autosomal DNA, they each share unique patterns and amounts of DNA with him. Notably, all four only share at one small spot on Chromosome 11.

Click on the chart to enlarge and get a closer look

I am also able to compare our known cousin to descendants of the women above to demonstrate what occurs when the DNA is passed to successive generations. Second cousins once removed would be expected to share half as much DNA as a second cousin (1.563%) and a second cousin twice removed would share half of that (.781%), the same percent as a third cousin. My sisters and I are all second cousins once removed from our known cousin. I share 1.08% and  my sisters share 1.84% and 1.38%. For second cousins twice removed, the actual percentages found in this study are .38%, .73%, .84% and .57%.  Below are four charts comparing our cousin to various family members, demonstrating how the DNA inheritance changes as it is passed down. All of the charts are laid out in the same way - comparing one of the second cousins and then two successive generations. All charts can be enlarged by clicking on them.

Note: On Chromosome #8 there is an unaccounted for small match. This match does not show in any other family member and may be a psuedo-segment

Note: On Chromosome #22 there is an unaccounted for match, This may be from inherited from the paternal side.

 

**Update - In the comments below, Dr. Ann Turner makes an important point about these four charts. She writes, "In addition to showing how shared segments vary in size and position, the multi-generation diagrams also show how the segments are inherited in an all-or-nothing fashion much of the time, especially as the segment size grows shorter. The longer segments naturally have a higher probability of being split by recombination."

Known Relative Studies with 23andMe: Great Grandchild DNA Inheritance

Great Grandchild Inheritance Pattern

I am very fortunate to have the opportunity to see the inheritance pattern of a great grandchild in my known relative studies at 23andMe, so I decided to share it. For those of you who are not familiar with the 23andMe user interface, the above chart is an illustration of the 23 pairs of chromosomes that we all possess. For simplicity, only one chromosome is displayed to represent each pair, thus the 23 bars. Using the Family Inheritance Advanced tool one can choose to compare selected individuals and a chart is generated to illustrate the shared DNA between them.

In this chart, the light blue is the shared DNA with the mother, the light green is the shared DNA with the grandmother and the dark blue is the shared DNA with the great grandmother. Of course, the parent and child (light blue) share DNA across all 23 of the chromosomes, as would be expected. This represents the 50% of shared DNA between the child and parent. The grandparent and child (light green) usually would share approximately half as much DNA with the stretches being broken up into smaller blocks. In this case, the child inherited a larger than expected amount of shared DNA with the grandparent at 31.54% (expected ~25%). The great grandparent and child (dark blue) should share approximately half as much DNA as the child and the grandparent, with the blocks broken up into even smaller fragments of shared DNA. In reality, the percentage is less than half at 14.75% of shared DNA, which is still rather high compared to the norm (expected ~12.5%).

As you can see, the percentages will vary from the expected values. Notably, 31.54% is the highest sharing I have seen between a grandparent and child in my research so far. Since the child inherited 50% from the maternal side, there is only ~18.46% that could have been inherited from the other maternal grandparent, which is well below the expected 25%.

Notice that as the relationship gets more distant, in general, the shared blocks of DNA get smaller, disappearing completely on some of the chromosomes. On Chromosome 13, there are no stretches of shared DNA (that meet the threshold for this tool) between the grandparent and child. This means that on Chromosome 13, this child has inherited significant DNA from the other grandparent's ancestors (in this case, the maternal grandfather). Following this same pattern, on Chromosomes 6, 13 and 14, the great grandparent and child do not have any significant blocks of DNA. Also notice on Chromosome 10, the grandchild inherited the entire maternal grandmother's chromosome (light green across the entire bar). That means that Chromosome 10 has no (significant) DNA from the maternal grandfather.

Please remember that, in this case, we are only looking at half of the child's chromosomes. The child has another set of 23 chromosomes inherited from the father. Since we are not comparing the child with any paternal relatives, none of those chromosomes are represented in this chart or analysis.

**For more posts on my family studies, please see here. **

Known Relative Studies with 23andMe: Expected Percentages

I have had quite a few known relatives test with 23andMe recently. In the coming months, I will be writing a number of posts based on these results. As an introduction, I wanted to review some of the information that 23andMe and FTDNA provide in their FAQs regarding their autosomal DNA tests, Relative Finder and Family Finder.  All of these percentages are estimates and will vary due to the random nature of genetic inheritance. The following statistics apply to both 23andMe's Relative Finder (RF) and FTDNA's Family Finder (FF).

Expected percentage of shared DNA between:
Parent/child/siblings = 50%
Grandparent/grandchild/aunt/uncle/nephew/niece/half-siblings = 25%
1st Cousins/great-grandparent/great aunt or uncle/grandnephew or niece = 12.5%
1st Cousins once removed = 6.25%
2nd Cousins = 3.125%
2nd Cousins once removed = 1.563%
3rd Cousins = .781%
4th Cousins = .195%
5th Cousins = .049%
6th Cousins = .012%
7th Cousins = .003%
8th Cousins = .001%

The likelihood of detecting shared DNA with a known relative significant enough to show up in RF or FF:
1st Cousins and closer: 100%
2nd Cousins:  > 99%
3rd Cousins:  ~ 90%
4th Cousins: ~ 45% (FTDNA says > 50%)
5th Cousins: ~ 15% (FTDNA says > 10%)
6th Cousins and more distant: < 5% (FTDNA says < 2%)

In some families, there will be situations that will complicate the above predictions, such as cousin marriages and half-siblingship, but, in general, they are the guidelines that should be used in analysis and comparisons.

Further reading from this series -
Known Relative Studies: Great Grandchild Inheritance
A Success Story and the Randomness of Autosomal DNA Inheritance (Fourth and Fifth Cousins)
Known Relative Studies: Second Cousins 
Known Relative Studies: More Second Cousin Comparisons 
Known Relative Studies: Second Cousin Comparisons, Allen Great Grandparents
Known Relative Studies: Second Cousins or Half Second Cousins 
Known Relative Studies: Identifying DNA from Great Grandparents Using Second Cousin Comparisons
Known Relative Studies: I Found My Third Cousin Today! 
Known Relative Studies: A Third Cousin Comparison and More Random Autosomal DNA Inheritance
Known Relative Studies: Purdy Fourth and Fifth Cousins
Autosomal DNA Matching and the Importance of Testing Multiple Family Members (Ninth Cousins)
Ratekin Seventh Cousin
A Second Cousin Adds to My Chromosome Map and Answers a Nagging Genealogical Question