I have been trying to find the birth father of my 1/2 sister through her DNA results and genealogy. I have been able to narrow things down to one specific family but not a specific person. There are 5 or 6 possible bio father's in one group & 20+ in the "once removed" group.
Now my question is this: My 1/2 sister has a son. As he is a male, would a yDNA test help to narrow down a specific person?
Would the biological father's mother's DNA show or just his father's?
Thanks for any help you can give.