DNA testing of two descendants.

Question

What about only children. I had one biological brother and he is now desceased. I am the only living descendant of my parents. What do you do about the two descendants must be tested rule in this case?

Comments

I don't know much about DNA testing but I think you and your brother would share pretty much the same DNA as well as a brother and a sister could.  The two descendants would mean cousins so that you could sort of triangulate into the past. like if you could find a descendant cousin you could look for markers that would also prove both of your relationships to a likely common ancestor.  I think everbody has cousins although I guess it could be possible if all your forefathers and mothers were only children back throught the ages.

Answer 1

Hello Allice,

For autosomal DNA, one option is to test a third cousin or closer relative.  If you share the expected percentage of autosomal DNA for that relationship then you can confirm the ancestors on each of your ancestral lines back to (but not including) the shared ancestral couple.

Sincerely, Peter

Answer 2

I agree with Peter about doing an autosomal DNA test for a third cousin or closer.  Specifically, in my Dad's paternal side of his tree, we now have autosomal DNA tests from 10 different people (me, my Dad, my Uncle, a first cousin, a first cousin - once removed, four second cousins/1X/2X-removed, and two third+ cousins).  Most of our tests match one another - and all 10 match at least one of the other tests.

The great thing about doing tests with cousins is that you get great leads on specific parts of your tree.  The caveat is that you have to know the cousin's tree pretty well to be able to rule out other possible recent common ancestors.  The autosomal DNA test shows you exactly how you are related.  Then - when you find new additional matches who share a DNA location with you and your cousin - this is often a great lead for your tree.

Answer 3

I would not worry so much about the 2 person rule regarding checking the confirmed with DNA option.

DNA will assist you in improving the quality of your tree by knowing as many relatives who have taken or who will take DNA tests from both sides of your family.  In particular, your tree indicates your mother is still with us.

Without question, I would test her first on all 3 major DNA services and 2nd, test yourself on 23andme. Find those cousins who you probably don't know of first to see what cousins you do know, who might benefit you the most.