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This project’s aim is to help South African Geni users use atDNA results to find missing links, and it is for users whom uploaded atDNA results to Geni and are unsure on how to use it to complete trees. It is also written in October 2018 using the current methods employed by Geni to show and match atDNA results, which are subject to change in future.
Assuming you are such a user, with an incomplete tree, with the sole aim of using your atDNA results to find missing links, this is the project for you.
Mathematically (i.e. based on some assumptions) your chance of having a common South African ancestor born 1640-1720 is 344999 out of 345000 (i.e. almost certain) if you can tie the majority of your roots to the South African progenitors. Translating the mathematics to words: It is almost a certainty, between most South African profiles, to find at least one common ancestor roughly 10 to 12 generations ago, should your South African tree go that far back.
This complicates using atDNA results to verify the accuracy of family trees for the South African Caucasian population – i.e. the relationship you are really looking for, to solve the missing part of your South African tree using atDNA, may be hiding behind another close relationship. On average, the Caucasian population here (with trees tracing back to early progenitors) are all 4th to 9th cousins!
With recent progress in atDNA is has become possible to test the accuracy of trees and find common ancestors 8-10 steps apart, between two profiles both with atDNA uploaded. Translating steps to what Geni interprets as generations, when you have an atDNA match, it means that your actual relationship is at most 10th cousins (usually at most 8th cousins), or also what Geni calls a xth Cousin with y steps removed (the sum of x and y is 8 to 10 at most) – whilst the “Match Quality” would be 50-60% of the “Relationship” length – stated using Geni terms.
You may note that 8-10 steps (using atDNA) at most is much less than 10 to 12 generations (mathematically), and this is where atDNA really shines in its potential usefulness, for the probability of a common ancestor reduces significantly per generation – simply put: if just considering 1 vs 2 generations, you have 2 parents (1 generation) but 6 ancestors (2 generations), a 200% increase measured in terms of number of people.
Below are the steps to be followed:
Your atDNA matches are shown under the DNA tab under your profile (1st step). Then it is found by clicking under Autosomal DNA on the link: “There are xyz profiles on Geni with autosomal DNA that matches your own”. By default, this list is ordered by “Match Quality” i.e. showing those profiles which are closest to you first.
Your task is to confirm that the value in the Relationship column is not more than twice the “Match Quality” column, by adding the Xth cousin Y times removed in the “Match Quality” column and multiplying it by 2 (add 1 as a safety measure). If the Relationship is within this range, it means that both your tree and the person whom you matched atDNA with, have trees on Geni which seems to be correct – “the result can be verified”.
However, your aim is to focus on those results which are not within range. You should open all the profiles which are outside of range, and:
1. Make sure that the relationship pin is set to yourself. Then refresh the "How are you Related" box near the top of the open profile. It might refresh the path to be within normal range.
2. If the profile is still outside of range: View the other profile’s tree in Tree View, and select at the bottom to go 5 generations back (under Tree View view, at the bottom, select options “Show only direct ancestors” and “5 ancestors and 1 descendent”). With that view open, check if the profile’s tree is complete, i.e. it has generations going back fully for all ancestors. (doing this manually will take a lot longer, and not really add any worth!)
3. If the other profile’s tree is complete, keep it open.
4. If the tree is not complete, try to complete it to the best of your ability. If you cannot complete the tree, then the results can be discarded for now – close it.
a. The remainder of this project deals only with atDNA matches where the other profile’s tree is complete.
5. Find more atDNA matches with completed trees, where the Geni “Relationship” is outside of the comfort range.
6. Then view all those outside comfort range trees and find a common denominator part of the tree, which are in those trees, and not in yours. That should point you towards where you are missing information, or perhaps you could be guided by surnames or names.
This is a rough work, and always a work in progress, but with the interest of making the best of what we have. Your contributions and questions are valued.