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To my paranoid cousin who let me take a DNA sample for genetic genealogy:

Yes, dear, there’ve been some news stories lately about the police getting leads in a 20-year-old murder case using DNA that has been tested for genetic genealogy purposes. CNN carried the story; even London’s Daily Mail newspaper did.

DNAYes, dear, I know you said you never want the government getting any information about you, not even your name if you could help it.

Yes, dear, the article does say the police in this case — a murder of a 16-year-old girl in Washington State in 1991 — got a name by hiring a genealogist to check through DNA samples. Robert Fuller, as a matter of fact.

But no, dear, unless there’s something about you that you haven’t told me, you are not going to wake up some morning and find your name in a newspaper article about a murder because you let me take a DNA sample to help our family history.

Understand, dear, that the name the police got using DNA tested for genealogy is that of a man who settled in Massachusetts, oh, about 380 years ago, give or take.1 He’s not exactly on the FBI Most Wanted list at the moment. I’m not given to wagering, but it’s a pretty safe bet that that Robert Fuller did not kill anybody anywhere 20 years ago, and that the police in Washington State are not out looking for him to bring him in for questioning.

All the police were able to get was the clue that the person who left his DNA on the crime scene when that girl was killed is probably a descendant of Robert Fuller, who probably still has the surname Fuller. (Since that kind of DNA is passed from father to son,2 and the first known person with that DNA was a Fuller, all of his direct male descendants should also be Fullers. Unless, of course, a boy somewhere in the last 380 years happened to take his stepfather’s name or there was an adoption or somebody’s mama was catting around or…)

And understand, dear, that except in these really extraordinary cases where the crime is very serious and the police have no clues at all, the chances that the police are going to turn to genealogy DNA databanks is pretty slim. Why? Because if the police have probable cause to believe that a crime has been committed and that you committed it, they can walk into any judge’s office in this country and get a search warrant that will let them pick you up, trot you down to the nearest medical facility, and take whatever blood or saliva they want for a DNA sample and they’ll use their own lab, not 23andMe or Family Tree DNA, to do the tests they want.3

And if the police don’t want you to know they’re on to you, they can sneak a DNA sample. They could watch you smoke at a bar and collect the cigarette butts when you leave. They could set up a phony job interview and give you a bottle of water to drink or a piece of cake to eat (in one case they gave the suspect a bottle of water AND a piece of cake and got DNA samples from the bottle and the fork). They could even send you something in the mail and get a DNA sample from the saliva you use on the flap of the envelope when you return that “send this in to WIN!” form.4

So the bottom line is: no, dear, the DNA testing you and I did really isn’t going to have the police at our doorsteps in the morning.

So no, dear, you and Aunt Tilly and all those other cousins out there should NOT start saying no when I ask you to let me get your DNA tested. The DNA testing we do for genealogy is NOT going to have the police at our doorsteps in the morning.

And yes, dear, of course I still love you.


  1. Bryan Johnson, “Genealogy brings new twist to cold case murder of Fed Way teen,” ( : accessed 10 Jan 2012).
  2. “What is a Y-chromosome DNA (Y-DNA) STR test? What will I learn?,” Family Tree DNA ( : accessed 10 Jan 2012).
  3. See, for example, United States v. Allen, 631 F.3d 164, 167-168 (4th Cir. 2011) (“Baltimore and federal authorities sought and obtained … the … warrant (that) authorized the collection of Allen’s DNA”).
  4. The Office of the Denver District Attorney collects and reports on these kinds of cases and puts the facts online. “Fourth Amendment DNA Cases,” DenverDA ( : accessed 10 Jan 2012).
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