Re: If paternity depends on 1 of 2 full bio brothers and only 1 is tested?

Hello Lisa,

I am not a genetic counselor, a doctor or a lawyer so *do not* use my opinion for legal proceedings. I am a forensic scientist and understand paternity typing and statistics. The tests performed in 1998 most likely were DQa and Polymarker DNA profiling which we used for criminal cases years ago. And your lawyer is correct in that the test was confident in determining "who could not be the father". And that wording is the manner in which results were given to a client when requesting paternity typing. The 96.2% statistic is somewhat low; I have seen 99.9%. Of concern to me is that the other possible father is a blood brother of the individual who took the test. Since the available genetic pool of information that can be accessed is limited, the brothers will certainly have more similiar genetic profiles then 2 random individuals.

If possible, the remaining brother should have a DNA paternity test conducted. In lieu of that, more sophisticated DNA tests are now available (STR) that should provide better statistical evidence.

Good Luck.

Dale L. Laux
Forensic Scientist