We’re more closely related than you think

How reliable is DNA in identifying suspects? – Los Angeles Times

The search went ahead in January 2007. The system did not go down, nor was Maryland expelled from the national database system.

In a database of fewer than 30,000 profiles, 32 pairs matched at nine or more loci. Three of those pairs were “perfect” matches, identical at 13 out of 13 loci.

People have been talking about this pretty much since the first DNA profiles were done, because no one knows how many people match at how many points. And the first generation of criminals convicted with DNA profiles had matches at maybe 7 loci, max. (Yeah, and the FBI was arguing that the odds were billions to one against another person having the same alleles back then too.)

Not only is it, I believe, criminally (as in deliberate obstruction of justice) irresponsible of the FBI to be throwing up lies in an attempt to block these kinds of searches, it’s also an affront to the very science DNA profiling is based on. Knowing how many close matches there are among members of a sample that big could tell us all kinds of things about the human race.

(And what’s worse yet, all the lies about odds of trillions to one don’t really help a prosecution that’s made its case properly. Even if there are a million other possible suspects based on DNA, that doesn’t produce reasonable doubt unless the prosecution is unable to show that none of those suspects were at the crime scene.)

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