Sorting matches

[Sara291]

Finally figuring out some of this stuff . . Question though . . I like the option I can click - In common with or not in common with when looking at matches. I'm confused though since I tested my son and me and when I click not in common with my son lots come up. Wouldn't my son match all my matches as well? Well at least semi close? Some of these are listed as 2-4th cousins on my since yet don't even show up as a match for my son. I understand my son having lots of not in common with me with in his account since he would have matches from his other biological side but shouldn't all of my matches be matches for him as well since I'm his mother. I wasn't expecting so many pages that I'm matched to that he isn't. I know we get a different level of DNA from each parent however it was tons of pages worth of matches that should be connected to him. Super curious what my daughters results will be (they are full siblings).

[thetick]

Finally figuring out some of this stuff . . Question though . . Wouldn't my son match all my matches as well?

Your son only has about half of his autosomal DNA from you. The other half is from his father.

[Sara291]

Yes I understand that but shouldn't my 2 through 3rd cousins be related to him as well?

[KATM]

Yes I understand that but shouldn't my 2 through 3rd cousins be related to him as well?

You might want to review the Autosomal DNA Statistics Chart at ISOGG (International Society of Genetic Genealogy), which is a good place to learn more.

Also take a look at Blaine Bettinger's Shared cM Project, and Kelly Wheaton's Beginner's Guide to Genetic Genealogy.

Here's a page about sibling matches and differences, for if/when you get your daughter tested Similarity of Siblings

This one might be a bit confusing, but shows How Many Genomic Blocks Do You Share with a Cousin?, and at least the chromosome diagrams give an idea of how DNA can be inherited.

[MMaddi]

Your son shares 50% of his DNA with you and 50% with his father. Or to put it another way, he only has 50% of your DNA.

So, if you share segments with an estimated 2nd-4th cousin, through random recombination he didn't receive those segments in the 50% of DNA he shares with you or at least not enough of that DNA to satisfy FTDNA's matching algorithm. If you have other children and they tested, they would have a good chance of sharing enough DNA with your 2nd-4th cousin to be declared a match. They received those segments in the 50% of DNA they share with you that your son did not receive.

[Biblioteque]

And, the same randomness applies to your cousin matches who are siblings. I have matches with three 3rd cousins who are siblings; and share the following cMs with each:

Bro A - 115 cMs
Bro B - 78 cMs
Sis A - 65 cMs

And of course, I share random segments with each. With Bro A, I even share, in addition, another different chromo.