Monday, November 13, 2017

FTDNA's Holiday Sale 2017



Some of you may have already noticed that the FTDNA Holiday Sale was launched yesterday afternoon. Below is the official company price list that was handed to attendees of the group project administrators conference immediately after the launch:



Those of you who have observed these sales for the last few years, have come to expect additional presents to appear on your FTDNA page each Monday during the sale which is expected to run through December.


When you click on the "Holiday Reward" icon, a discount code is revealed which is good through the following Sunday night Houston time. For example this week my coupon is good for an additional $20 off the sale price of a y67 marker test. If you manage multiple accounts, be sure to check each of them each week to maximize you chances to find the best discounts.

A secondary marketplace has already grown up to regift these "Reward" codes. If you received a y67 discount code as I did but instead need a mtDNA test, you can deposit your unneeded code(s) at locations like this site and "shop" for discounts on the tests you need. Check back often as the bigger discounts will be posted at any time during the week as more people log into their accounts for the first time that week or they decide they cannot use a particular test. There can be some strategy involved as you decide whether to take advantage of a small discount or wait a week or so as you hope to locate a larger discount.

Happy Holiday shopping to all of us as we cooperate to build our cousin matching databases to benefit us all!


Tuesday, November 7, 2017

With Great Haste We Make Slow Progress



FTDNA has been "evolving" our BIG Y results for a couple of months now. As a part of that process we were regressed back to the most recent ySNP for which we had tested positive separate from BIG Y. In my case that was back a little over four thousand years ago (R-DF13). 

This morning the evolution of my results has progressed to the point that my trail brings me down into the genealogical era again. It is good to be back. This process is not complete. The numbers in the right column will continue to increment as the results of others are "evolved" as well. It appears that about half of the results have now completed that process.  

My BIG Y Matching results are of November 7th
The three individuals with whom I am now showing matches on the bottom two steps share my surname and are also descendants through three different sons of my 6th great-grandfather who died in southern Maryland in 1733 -- clearly in the genealogical era. 

Another man who does not share my surname is expected to join the 3 matches on the second level when the processing of his results are upgraded in the near future. His family and mine were associated with each other in both Maryland and North Carolina. He was my earliest close STR match (an exact 12/12) when I first tested in 2004 and he is a 109/111 STR match today. I am eager for his results to be migrated so that I can further explore which of the three sons of my 6th great-grandfather his genome seems to be most closely associated with. Prior to Big Y testing, documents seemed to indicate that he was likely to be associated with the third son -- from whom I descend. In the first round of BIG Y testing he seemed genetically to be more similar with a descendant of the second son who's line never left Maryland. If that is the case, one of our biological paternal lines may have been rerouted around 1700 or before. I hope the new tools we are being given by FTDNA will help me sort this out.

I will be all ears and full of questions when I get to the 13th International Conference on Genetic Genealogy this weekend in Houston.



Friday, October 6, 2017

I Got It Wrong: A Retraction/Correction



Back on July 17th I published a blog with the heading How autosomal DNA is inherited: 3 siblings compared. At the time my son Jon was bothered by part of it related to the passing of DNA from great-grandparent to great-grandchild but I was too dense to comprehend his objection. Yesterday after more than six thousand seven hundred page views, Philip Gammon commented:

Hi, I'm surprised that no one has pointed out that calculation of the contribution from great-grandparents in the article is incorrect. The contribution of each pair of great-grandparents is not 25%, it is equal to the contribution the great-grandchild receives from the grandparent. This figure varies significantly as pointed out in the earlier paragraphs but this information is then ignored in the latter half of the article. 
This time I finally got the point. I wish to publically thank Philip for his initiative in bringing this error to my attention. I would like to think that many of the rest of my readers also noticed this incorrect conclusion on my part but were too kind to bring it to my attention. However, if we truly are going to consider ourselves to be citizen scientists, we must take on the responsibility offering constructive peer review of the work of our colleagues. That is how we all learn. What follows is a revision of that original post.


Inheritance of aDNA from grandparents:


If you know how much aDNA you inherited from a grandparent or great-grandparent, can you calculate how much you inherited from that person's spouse?

By now most of us know that each of us get half of our autosomal DNA from our mom and half from our dad. But how we inherit from earlier generations of our ancestors is less well understood. We are generally told after that first generation the inheritance pattern is random. However, we often see charts that show we should expect to inherit about 25% from each grandparent and 12.5% from each great-grandparent, etc. Are there any additional rules?

Below is a small case study that explores these issues:



Inheritance from maternal grandparents are shown in the left hemispheres above and paternal contributions are in the right hemispheres.

The chart above shows how much aDNA each of three brothers inherited from each of their grandparents. Only the middle one, Grandson 2, came close to the 25% average we might expect. However, note that each grandson inherited exactly 50% from his maternal grandparents and 50% from his paternal grandparents. However, the amount inherited from each individual within a set of grandparents varied considerably. The exact percentages can be seen in the table below.


As noted above Grandson 2 came the closest to the theoretical 25% inheritance rate. The aDNA inherited by Grandson 1 was skewed somewhat from that distribution. The practical implications for even this amount of variation can be important to your genealogical research. 

In this example the maternal grandfather is Ashkenazi -- a group that statistically has been over sampled in genetic genealogy databases. He had more than eleven thousand matches in FTDNA's Family Finder. The maternal grandmother came from an area in Eastern Europe very near the origin of her mate; but she was non-Ashkenazi. She had less than five hundred matches in Family Finder. The 4% difference in the amount of Ashkenazi DNA inherited resulted in Grandson 2 having more than five thousand matches while his full brother, Grandson 1, had about a thousand matches less. This also had a noticeable difference in their ethnicity predictions. 

When Grandson 3's Family Finder results are reported, it is expected that his matches and ethnicity predictions will vary ever further from those of his two brothers -- particularly Grandson 2. As we will see below, Grandson 3 inherited more aDNA from his great-grandfather -- the father of his maternal grandmother -- than the 15% he inherited from his Ashkenazi grandfather. This variation from the expected 25% from each grandparent could have been influenced by the preimplantation genetic screening process that selected a fertilized embryo that did not include an autosomal dominant gene that leads to a potentially fatal heart defect.  

All the results above are based on actual test results. However, if one of the grandparents had not been tested, we could have calculated their contribution. Even if two had not tested we could have calculated their contributions IF we had results from each of their spouses. You have probably already figured out that the contribution of the missing grandparent spouse would be 50% minus the contribution of their known spouse.


Inheritance of aDNA from great-grandparents: 

This kind of calculation becomes more relevant in the current case when I took a look at contributions from great-grandparents. We only have actual test results from one great-grandparent who was tested a decade ago about a year before he died in his mid 90s. So we can use his actual test results and also use them to calculate the aDNA contribution of his wife. By now you probably can guess that the hypothesized contribution of the non-tested great-grandmother will be constructed by subtracting his tested aDNA amount from the tested contribution of the relevant grandparent. The latter would equal the total contribution of each pair of biological great-grandparents.

For the oldest brother it turns out that the tested great-grandfather had contributed 12.4% of his autosomal DNA. This is very close to the theoretical 12.5%. In this case the grandmother had contributed about 28%. This left 15.6% for the great-grandmother to have contributed.


Great-Grandson 1




aDNA from great-grandparents

Grandson 1
Grandson 2
Grandson 3
Tested Great-Grandfather

12.4%

10.3%

16.6%
Tested 
Grandmother

28%

24%

35%
Calculated Great-Grandmother

15.6%

13.7%

18.4%
All other Great-Grandparents

72%

76%

65%


In all cases the great-grandsons received more aDNA from the great-grandmother than they did from the great-grandfather. The tested great-grandfather had passed down 10.3% of the aDNA of the second brother and 16.6% of the aDNA of the third brother. In fact the 16.6% of his overall aDNA that the third brother received through his maternal grandmother and mother was more total aDNA than this brother had inherited from his paternal grandfather (15%, see above). This result was surprising but perhaps not unusual. We are preconditioned to expect that we received about one half the amount of aDNA from each ancestor in each receding ancestral generation. In this case that expectation was confounded because of the large amount of maternally inherited aDNA that the mother of the brothers had passed down to her third son. Although the mother had inherited half of her own aDNA from each of her parents, what she passed down to the third son had disproportionately over-represented what she had inherited from her mother by a ratio of more than two to one -- 35% to 15%.

The second son inherited less of the calculated contribution from his great-grandmother than either of his brothers in part because he inherited less of his grandmother's aDNA. He inherited 13.7% versus their 15.6% and 18.4%.




Great-Grandson 2


The third son inherited the most aDNA from the tested great-grandfather and did so by a considerable ratio. Although his 16.6% inheritance does not seem like a big difference from the 12.4% of one brother and the 10.3% of the other, it is about 35% more than one and 63% more than the other. In terms of inherited ethnicity and traits, these differences could matter. 

Great-Grandson 3



The Takeaways:
   
1. We inherit 50% of our aDNA from each parent; 50% from each set of grandparents; then what we inherit significantly different amounts from each set of great-grandparents, etc.
2. We often inherit significantly different amounts of aDNA from each member of a set of ancestors.
3. Even full siblings often inherit significantly different amounts of aDNA from each of their grandparents and great-grandparents.
4. These differences can significantly affect the numbers of autosomal matches reported for each sibling.
5. These differences can significantly affect ethnicity estimates.
6. These differences can significantly affect health and other heritable characteristics.
7. The contributions of some ancestors can begin to fade significantly within two or three generations while those of others can remain robust much longer.
8. If you have test results for at least one grandparent or great-grandparent, you can calculate the aDNA contribution of their partners.

Monday, October 2, 2017

Test ALL family members even full siblings



Earlier this year I reported on what I was learning from the autosomal DNA tests of my three grandsons who are now 10, 7 and 3. I am continuing to learn more as I examine their results in different ways. They were all tested through MyHeritage and then their results were imported into FTDNA's Family Finder to be able to compare them more easily with other family members.

The earlier posts can be viewed: 
In this post I will comment on what I learned when I mapped segments of my grandsons' DNA using Kitty Cooper's tool and Family Finder's Chromosome browser. 




For those of you who do not personally know these fine young men, the takeaway from all of this is to realize how each inherited very different segments of DNA from each of their 4 grandparents and the one great-grandparent from whom we have a DNA sample. The implications of this for genetic genealogists are that when we are administering autosomal tests we should test as many family members as possible. Even full siblings will have quite different match results. 

Numbers of matches reported will depend greatly on the extent to which autosomal DNA testing has penetrated the geographic and ethnic groups from which the test takers descend. In the case above, one grandfather is Ashkenazi and his spouse comes from another area of Eastern Europe but is not genetically Ashkenazi. The differences in their numbers of matches is astounding. These match numbers carry down two generations to their grandchildren. It depends on how much of their autosomal DNA each of the grandchildren inherited from each individual grandparent.

Oct 1st, 2017
Matches on Family Finder
Ashkenazi
Simon
5,999
26%
Noah
4,944
22%
Benjamin
3,732
15%
Monika Deutscher Katzel
502
0%
Lester Katzel
12,787
97%
Dave
3,306
0%
Arlene
2,427
0%
Shana (Katzel) Dowell
6,930
42%
Frederick Deutscher
466
0%

When you are formulating a DNA testing plan, administer an autosomal DNA test to as many family members of each generation as you can possibly afford to test. Each person tested will contribute something to the family mosaic. The results in all families will not be as dramatic as in this family but the results that each additional person contributes can be just as significant.


As a postscript, the contribution shown above for grandmother Monika could also be attributed to her mother as her father's contribution is accounted for separately. 

Monday, July 17, 2017

How autosomal DNA is inherited: 3 siblings compared



If you know how much aDNA you inherited from a grandparent or great-grandparent, can you calculate how much you inherited from that person's spouse?

By now most of us know that each of us get half of our autosomal DNA from our mom and half from our dad. But how we inherit from earlier generations of our ancestors is less well understood. We are generally told after that first generation the inheritance pattern is random. However, we often see charts that show we should expect to inherit about 25% from each grandparent and 12.5% from each great-grandparent, etc. Are there any additional rules?

Below is a small case study that explores these issues:



Inheritance from maternal grandparents are shown in the left hemispheres above and paternal contributions are in the right hemispheres.

The chart above shows how much aDNA each of three brothers inherited from each of their grandparents. Only the middle one, Grandson 2, came close to the 25% average we might expect. However, note that each grandson inherited exactly 50% from his maternal grandparents and 50% from his paternal grandparents. However, the amount inherited from each individual within a set of grandparents varied considerably. The exact percentages can be seen in the table below.


As noted above Grandson 2 came the closest to the theoretical 25% inheritance rate. The aDNA inherited by Grandson 1 was skewed somewhat from that distribution. The practical implications for even this amount of variation can be important to your genealogical research. 

In this example the maternal grandfather is Ashkenazi -- a group that statistically has been over sampled in genetic genealogy databases. He had more than eleven thousand matches in FTDNA's Family Finder. The maternal grandmother came from an area in Eastern Europe very near the origin of her mate; but she was non-Ashkenazi. She had less than five hundred matches in Family Finder. The 4% difference in the amount of Ashkenazi DNA inherited resulted in Grandson 2 having more than five thousand matches while his full brother, Grandson 1, had about a thousand matches less. This also had a noticeable difference in their ethnicity predictions. 

When Grandson 3's Family Finder results are reported, it is expected that his matches and ethnicity predictions will vary ever further from those of his two brothers -- particularly Grandson 2. As we will see below, Grandson 3 inherited more aDNA from his great-grandfather -- the father of his maternal grandmother -- than the 15% he inherited from his Ashkenazi grandfather.

All the results above are based on actual test results. However, if one of the grandparents had not been tested, we could have calculated their contribution. Even if two had not tested we could have calculated their contributions IF we had results from each of their spouses. You have probably already figured out that the contribution of the missing grandparent spouse would be 50% minus the contribution of their known spouse.


[The portion below is being revised to take into account the error in my thinking pointed out by Philip Gammon in his comment below. That revision will be posted tomorrow, October 6th.]

This kind of calculation becomes more relevant in the current case when I took a look at contributions from great-grandparents. We only have actual test results from one great-grandparent who was tested a decade ago about a year before he died in his mid 90s. So we can use his actual test results and also use them to calculate the aDNA contribution of his wife. By now you probably know that the hypothesized contribution will be constructed by subtracting his tested aDNA amount from 25% -- the total contribution of each pair of biological great-grandparents.

For the oldest brother it turns out that the tested great-grandfather had contributed 12.4% of his autosomal DNA. This is very close to the theoretical 12.5%. This left 12.6% for the great-grandmother to have contributed.




However, the second and third brothers received a more uneven contribution from this pair of great-grandparents. One received a greater than expected amount from the great-grandmother and the other from the great-grandfather. The tested great-grandfather had passed down 10.3% of the aDNA of the second brother and 16.6% of the aDNA of the third brother. In fact the 16.6% of his overall aDNA that the third brother received through his maternal grandmother and mother was more total aDNA than this brother had inherited from his paternal grandfather (15%, see above). This result was surprising but perhaps not unusual. We are preconditioned to expect that we received about one half the amount of aDNA from each ancestor in each receding ancestral generation. In this case that expectation was confounded because of the large amount of maternally inherited aDNA that the mother of the brothers had passed down to her third son. Although the mother had inherited half of her own aDNA from each of her parents, what she passed down to the third son had disproportionately represented what she had inherited from her mother by a ration of more that two to one -- 35% to 15%.

The second son inherited more of the calculated contribution from his great-grandmother than either of his brothers. He inherited 14.7% versus their 12.6% and 8.4%.




The third son inherited the most aDNA from the tested great-grandfather and did so by a considerable ratio. Although his 16.6% inheritance does not seem like a big difference from the 12.4% of one brother and the 10.3% of the other, it is about 35% more than one and 63% more than the other. In terms of inherited ethnicity and traits, these could matter.




The Takeaways:
   
1. We inherit 50% of our aDNA from each parent; 50% from each set of grandparents; 25% from each set of great-grandparents, etc.
2. We often inherit significantly different amounts of aDNA from each member of a set of ancestors.
3. Even full siblings often inherit significantly different amounts of aDNA from each of their grandparents and great-grandparents.
4. These differences can significantly affect the numbers of autosomal matches reported for each sibling.
5. These differences can significantly affect ethnicity estimates.
6. These differences can significantly affect health and other heritable characteristics.
7. The contributions of some ancestors can begin to fade significantly within two or three generations while those of others can remain robust much longer.
8. If you have test results for at least one grandparent or great-grandparent, you can calculate the aDNA contribution of their partners.


Thursday, July 13, 2017

Ancestry.com has done it again! READ COMMENTS!



Ancestry.com has once again made a corporate business decision that emphasizes the ".com" at the expense of the "Ancestry" in the corporate title. The company announced in its official blog today that it will be limiting us to registering only one DNA kit to each membership account except in the case of minor children. The post was entitled "Enhancing Collaboration and Roles on DNA Results". Please read this before you order any DNA kits from AncestryDNA. Ancestry explains this change: 
As the AncestryDNA service has grown, we are increasingly hearing about families taking DNA tests together. Family members want easier and more powerful ways to collaborate with each other to make discoveries in their family story, all while still maintaining control and privacy of their own information. 
A couple of years ago I blogged my thoughts about the appearance that Ancestry believed they always knew more about what we needed as genealogists than we knew ourselves. That post was entitled Does Ancestry think we are NOT OK? and can be read by clicking on this link.

Today's announcement indicates that Ancestry is at it again. The more than two dozen responses posted in the first hour were uniformly those of disappointed genealogists who still are looking for chromosome browsers. They were not looking for Ancestry to force everyone to have a separate Ancestry membership for each kit tested. Peggy Dalton Druck raised a number of other similar decisions over the years that also have seemed counter to the interests of genetic genealogists but perhaps Ancestry hopes they will be favorable to the bottom line of the company. She was kind enough to allow me to include her comments below: 
I was going to order 3 more tests to have done in order to locate relationships within my family. I have been on Ancestry since 1997 and then full time since 2000.Every time you change something on ancestry it deletes a great deal off added things us researchers have added to the pages.I have one main tree and several other trees I research on.Now with this, it is ridiculous.I have stayed with ancestry all these years to prevent my research from being all over the internet.You sold off FTMaker and I can no longer use it for anything because of the last update they did to it messed my ancestry tree up so bad. You got rid of my fathers DNA from his Y 37 test and he is dead now and I can not use his dna numbers anywhere.You were not suppose to destroy dna in case someone wanted to to an upgrade like I wanted to do with my dad’s dna, but now his dead and you destroyed his DNA.Now you are doing this to all of us who have stuck by your company, helped to build the trees we have over all these years and now with our continuing work of verification with DNA you want to stripe us of all of our hard work we have done all these years.
It appears that we will have to deal with even more "orphaned" accounts in the future as a result of Ancestry's implement of this requirement to pay for separate accounts in order to remain actively involved with one's DNA and the matches that are made. As several others commented on the Ancestry blog, many of those we want to test have no interest in or ability to setting up and maintaining separate accounts but would rather delegate this responsibility to the family genealogist. These are often the older family members whose autosomal DNA is most critical for us to collect and preserve.

Ancestry, I wish I had hope that you would listen to us this time.

Saturday, June 17, 2017

Unintended Consequence?


We all are familiar with the stated inheritance of autosomal DNA: 50% from each of the parents then about 25% from each of the grandparents and 12.5% from each of the great-grandparents. But how often does it really happen that way? The 50% from each parent part seems to be an absolute. But are the grandparent contributions to our DNA distributed on a "Bell curve" centered on 25%?

When I first started analyzing how my grandsons inherited aDNA from their four grandparents, I only had aDNA results for two of them -- then age 9 and almost 7. I realized that they did not inherit the same amount from each. However, each pair of grandparents contributed 50%. When I was discussing this with my grandsons, the nine year old commented that if we were to test their youngest brother, the almost 3 year old would be more similar to his own than the results of the youngest brother would be with those of middle brother. I previously, posted about these results back in March:

Since I was trying to build their interest in DNA testing, I decided to test this hypothesis. At the very least it would give us a chance to talk about the difference between phenotypes and genotypes. This hypothesis was based on physical appearance--hair, eyes, etc. 

This grandson had already created a minor ripple in the play yard when he was in preschool. He had explained to his classmates the difference between boys and girls using anatomically correct terms. His mother is an obstetrician and had taught her sons the anatomically correct terms for the parts of their bodies. He seemed to be a grandson to whom I could pass on my interest in DNA. 

Toward that end I decided to test his hypothesis about how his genotype would compare with those of each of his brothers. This meant getting cheek swabs from an active boy who by then had just turned 3. The hardest part was to catch the 3 year old when he had not put food or liquid in his mouth for an hour. The swabbing his cheeks part turned out to be relatively easy by comparison.

aDNA of 3 full-brother grandsons received from grandparents
The results for the 3 year old just came back from the lab and his older brother's hypothesis has been supported. In the bar graph above, the 9 year old is in the middle row and the 3 year old in the back. It appears to me that the 3 year old is more similar to the 9 year old than he is to the now 7 year old (in the front row). However, that does not appear to be the breaking news in this chart.


The maternal grandfather contributed only 15% of the aDNA to the 3 year old after contributing 26% and 22% to the older grandsons. In fact the 3 year old inherited more aDNA from his maternal great-grandfather (16.9%) on a pass through among the 35% contribution of the maternal grandmother.


The 3 year old first had his DNA screened before he was implanted into his mother's womb. The purpose of this screening was to bypass a heritable and potentially fatal heart defect carried by the maternal grandfather. I have previously posted about Our DNA Day Miracle. Is it possible that in the process of screening out fertilized eggs that carried the Brugada gene, one was chosen that was an outlier from the normal amount of aDNA that would have been contributed by this grandfather? If so it was an unintended consequence.


Help please!

If any of you have any grandparent to grandchild aDNA inheritance data you are willing to share, please send it to me by instant message or email.