My father is born of unknown father and did a 23 and me DNA autosomal test. I thought I could use this test to potentially identify some relatives on this side but only very distant ones (at best 3rd cousin) could be matched.
In order to split the problem in smaller chunks, I was then thinking about trying to group the DNA segments into 4 clusters belong to each of his grand-parents. For that, I downloaded all his matches (more than 2000) from MyHeritage. I got regions with significant overlap with some with more than 400 matches.
The plan was to select some of these regions with overlap and see how much each match has an overlap with them. So I would get a matrix with the regions as column and the matches as rows and containing the overlap in CMs as value.
Then I would just need to calculate the correlation between the columns/regions, use some kind of clustering method and I would see clean clusters showing up. But of course that didn't happen, I'm just getting some kind of mess where the regions cannot be cleanly clustered.
I tried to filter the regions by number of overlap with a minimum and maximum value, minimum to have some overlap and maximum because I thought that there could some false-positive regions. But with little success.
What would you recommend as a way forward to do this grand-parents level clustering?
I think I understand why it does not work, because I have no way to tell on which chromosome (paternal or maternal) a segment is matching so I could have 2 matching segments from 2 people around the same position that wouldn't match with each other.
Is there a way around this problem?
I was thinking about matching on the start or end position since it is unlikely that two segments would have the same start or end without being related.
Or am I again missing something?