My Dad always loved the Logic puzzles in the Dell Puzzles Magazines. As I'm working on DNA matches today I can't help thinking about him. Not just because I am working on my paternal matches but that he would like the logic I am using. While I have had my DNA results and those of my Mom for over a year, my sister's results came in not long ago and we now have her kit at GEDmatch. She is a full sibling but there seems to be a good variation in the people which we match due to the randomness in the 50% which you get from each of your parents.. What does that mean for me? I can take her kit....run it with Mom's to phase out Mom's matches and create a kit of Sis' DNA she got from Dad...which I can then compare to my DNA which I got from Dad. If I know that one of us matches Dad's Mom along one segment..and it's a segment that we don't match along....I then know that the other one of us matches Dad's Dad along that segment which we don't have in common. After all...Dad only had two to offer...so you got one or the other.
Chromosome 4 on my Paternal side(which I can see by using the phased kit) I have a section from about 4-40 which I know I can attribute to my Paternal Grandmother's Morrow/Sutton lines. My Sister has NONE of these same matches along that same segment of her Paternal side(I can again distinguish her Paternal from her Maternal matches by using the phased kit of her DNA she got from Dad mentioned earlier). By this I can conclude that the matches along that segment for her are from my Paternal Grandfather's side and somewhere back along the Cook/Putman or King/Manire lines.
While this won't solve all of my unknowns, it is a big help in knowing where to look for the connection for these matches. So many times I wish that the matches had some idea of which side I match them along.This is one of the greatest things about having a parent and a full sibling that have also tested.