Welcome to the MacGregor Project DNA annual blog for 2021. This past year with the arrival of the virus has had an inevitable effect on the progress of the DNA project as everyone has been concerned to deal with the changes in lifestyle which have been needed. I thought therefore that I would use some of this update to explore some ideas, opportunities and limitations of autosomal testing – typically called ‘All my Ancestry’ or ‘Family Finder’, and also to share some thinking on the MacGregor Big Y results.
It is well known now that only males carry the Y chromosome and that this particular part of DNA is usually associated with surname (except for cases of adoption etc). It follows that for surname studies only males with the surname of interest can be tested for connection with a specific surname. For more recent family connections it can often be possible to find a male of the surname to do the test on a person’s behalf but going further back in time does not work so easily when thinking about autosomal (i.e. Family Finder) testing as I will explain. Inevitably genetic scientists will say that the following explanation does not cover all the possibilities and in some senses tends towards simplification: there is a certain inevitability about this when dealing with a wide and diverse audience.
I have often been asked “why can’t I be part of the surname project because my great great grandmother was a MacGregor?”, or “my ancestor was Rob Roy, can I do the DNA project to prove it (where the connection is through Rob Roy’s daughter or granddaughter)?”, or “why do the results of Family Finder not show in the surname project?”, or “why are surnames not included in the surname project?”. I hope to answer all these with the following text.
Everyone inherits autosomal chromosomes from their male and female ancestors. The proportions received from each ancestor varies, and also these tend to disappear over time as they are replaced by the DNA of succeeding generations. Otherwise, we would have millions of bits of autosomal chromosome going back into prehistory: having said which it IS possible that some of a person’s autosomal chromosome has survived from prehistory to the present day. Every generation doubles the number of forebears which you have: 2 parents, 4 grandparent, 8 great grandparents, 16 great great grandparents and so on. As you go back in time that number increases, so, around 1300, in the Medieval period, each person will have over a million ancestors and working on the principle that most people are related by ‘6 degrees of separation’ there must be many common ancestors between any two individuals.
We all have 46 chromosomes in total and two of these are the X and the Y: if you got a Y and an X chromosome from your parents then you are a male, if you got two X chromosomes then you are female. That leaves 44 chromosomes (2 x 22 pairs) for Family Finder to compare. Family Tree DNA’s Family Finder distinguishes between matches which arise from autosomal chromosomes (the 22 pairs) and the X chromosome and results are therefore shown for both autosomal chromosomes and also for what FtDNA refer to as X Match
[But note that, surprisingly, of the 5 matches on X Match out of the first 1000 Family Finder matches which I have, there is no detail in the graphics provided – I would be interested to know if others have found this to be the case also).
To explain this further let’s now take a specific example or two:On the familysearch.org website you can create your own fan chart of ancestry, and in an article Jessica Grimaud presents a filled-in fan chart: (https://www.familysearch.org/blog/en/genealogy-fan-chart/)
Fig. 1 Fan chart from www.familysearch.org
There is an amazing amount of genealogical material presented here and it is relatively rare for a researcher to be able to document quite so many generations. As a comparison here is my own fan tree which lacks detail from my mother’s side because I have not been able to ascertain with any certainty her Russian German mother’s ancestry.
Fig. 2 Fan chart Richard McGregor
I will begin by discussing an example of how this fan tree was used to identify a common ancestor with myself in Family Finder. I do not have a fan chart for the person who I match but there is a family tree for this person deposited on the Family Tree DNA website which contains sufficient information. We are listed as being 3rd to 5th cousins and these are the places that we have autosomal matches:
Fig. 3 Chromosome matches for myself and the other participant
This may look at lot but when compared with someone who is a 1st to 2nd cousin you can immediately see the difference. If you count the number of shared chromosomes in Fig 4 and Fig 5 you will see that the latter has many more. That indicates the first problem – the further back in time you go the less SNPs in common you will have with someone else and if it is 5 or 6 generations back then you have to work out which of up to 64 ancestors you actually match to:
Fig. 4: Richard McGregor matching chromosomes for 1st to 2nd cousin
Going back to the Fig 4 Family Tree DNA do a version of these results in graphic form which comes out as below (the shading represents the areas of match):
Fig. 5. Graphic form of shared SNPs between Richard McGregor and Family Finder match 3rd- 5th cousin
Working back with our researched genealogies we came back to a meeting point with a Georg Konrad Major born in 1797, two of whose children started the separate lines we descend from. I have over 4000 matches on Family Finder and only a few of these can actually be traced back to a specific individual shared between us – part of the reason for this is that not all participants share ancestral names or genealogical trees on the website. I have very few 1st to 3rd cousins and while it has been relatively easy to find the genealogical connections with these, when the relationship suggested is more distant, it becomes rather more difficult. There are quite a few examples where Family Finder participants have given ancestral names which match with those in my tree but none has led to a definite link.
Hopefully it is obvious that finding specific links with Family Finder relies on having access to genealogies which are as complete as possible and the closer the genetic connection the easier it is to identify the connection. When we are trying to identify a common ancestor who lived more than 250 years ago, it is vital to be able to eliminate other possibilities.
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Update on MacGregor DNA
This year has seen more participants upgrading to the Y700 test which has resulted in an expansion of the genetic tree of connections. There have been a large number of terminal SNPs identified, and on the grid at www.familytreedna.com/public/macgregor these are shown in the green colour. Sometimes these just represent a SNP that has been singly tested and is not the terminal SNP, and the best way to determine if you are looking at a terminal SNP is to assume that it will have a haplogroup (such as R or I) followed by a BY, FGC, or FT number [Big Y, Full Genome Corp or FamilyTree]. Quite often individuals who have tested to Big Y have SNPs which are not shared with others who have Big Y tested: these SNPs are known as Private SNPs and will be so identified until there are other participants found who have any of these SNPs – these will then be shown as shared SNPs and will indicate common ancestry between the individuals who bear them. When there are no SNP matches between individuals the Big Y results default back to the most commonly held SNP which is why some of those genetic MacGregors who have tested with Big Y default back to S690, which is the SNP that all genetic MacGregors have. As more results come in an individual with S690 might find that one of the Private SNPs becomes the terminal SNP. As I just indicated, in that case it might be reasonably assumed that the two (or more) individuals concerned share a more recent ancestor normally bearing the surname of interest.
Below I have copied the Big Y Block Tree graphic which is currently shown for the MacGregor group descending from Ian Cam. It is based on the format developed by Alex Williamson [The Big Tree]. I have removed individuals’ names for data protection reasons – however the terminal SNP can be cross checked on the results grid link given above to identify the earliest known ancestor where this has been filled in by the individual participant.
Fig 6: Block Tree (current) for MacGregor Ian Cam group
As another example I have chosen a McGregor result from what is labelled ‘McGregor distant group’ on the results grid:
Fig 7: Block tree diagram for a McGregor in the McGregor distant group
In this case the surname of participants varies across the grouping , starting with McKellar for the first two lines of descent followed by Robertson; no name given; Campbell; Stewart; McKellar, McKellar (which is the McGregor participant’s shared match); followed by McKellar; then unnamed at the far right, All Big Y participants can see their results presented in this way through their results page. However, it is important to say that if an individual’s terminal SNP has been determined without going through Big Y then this block graphic is NOT given in the participant’s results because some of the other SNPs which contribute to the Block Tree will not have been sequenced. For example, I determined my own terminal SNP BY4303 by deduction and testing, and not through Big Y, so I cannot see who else is close to me.
[Note: McKellar is considered a sept of Clan Campbell and is found across Scotland with authorities variously placing the origin in Argyllshire, Angus and/or Strathclyde].
Finally a McGregor distant result, but with a known Sutherlandshire connection:
In this case the rest of the Block Tree group matches are almost entirely called Nicholson (except for a solitary MacDonald). The individual’s McGregor result box does include an additional named individual whose surname is also McGregor – and in that case this participant and the other McGregor share an ancestor in the more recent past. Who this was might be established by comparing genealogies – the difficulty being that many Sutherland parish records are deficient for pre 19th century.
[Note: the name Nicholson in Scotland is said to derive from a lawyer who lived in Aberdeen in the 16th century, but there was also a family associated with the Isle of Skye who petitioned the Lord Lyon for recognition – which they got, on condition they were designated Clan MacNeacall of Skye]
Our own analyses which have been conducted by Prof. Neil McGregor is shown below (as at October 2020, although the previous date of May has been retained). This gives broadly the same result as Fig 7 above and represents the current state of our knowledge:
Fig 9: Ian Cam group Big Y results as presented by Prof. Neil McGregor
We have however identified an issue related to the first chip used by FtDNA.
You will see from the grid given below that the top group lack some results that are available for the lower group. We have contacted FtDNA about this:
Fig 10: Partial results grid Ian Cam group
You will have noticed that this year I have not used spider diagrams as in previous years. This is partly because comparatively little has changed over the year, but also because I prefer to offer individuals the possibility of seeing a spider diagram for their own result which is designed for them alone. You can see these spider diagrams by looking at previous versions of this blog. If you would like me to generate one for you ask me offline and suggest up to 12 individuals with whom you would wish to be compared by reference to their kit number. You can email me on chairmanATclangregor.org [change AT to @ - I just want to avoid spam!).
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