Family Finder Matches

[JoeDublin]

My cousin and I both did the Family Finder test. In attempting to use the results for genealogical research, can I assume that people we do not match in common are from my other side of the family not related to my cousin? Are the FF results that accurate?

Thanks for any help you can offer.

[MMaddi]

No, you can't make that assumption. Even siblings only share about 50% of long segments inherited from their parents. First cousins would only share about 12.5% of long segments inherited from the common grandparents. You can see this at http://www.familytreedna.com/img/fam...percentage.jpg

So, it's quite possible that you will have a match in Family Finder that your cousin doesn't have, but the segment(s) come from a grandparent that you and the cousin share. In a case like that, it's just that, due to random recombination of DNA, you received that segment and your cousin didn't.

This shows why, if you can afford it, it helps to get multiple cousins from both sides of your family to test Family Finder. Then you'll get much more coverage of the DNA segments of your grandparents and it will be easier to see on which side of your family the common ancestors with your matches can be found.