# If a close relative has DNA on file, can that potentially compromise you? **URL:** \ **Category:** Factual Questions\ **Created:** [January 30, 2017, 11:03pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620 "2017-01-30T23:03:14Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [January 30, 2017, 11:03pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/1 "2017-01-30T23:03:14Z")
My (full, biological, non-twin) brother is a convicted felon, therefore he has had to submit a DNA sample to the federal crime database. I am not, and have not. If I were to commit a crime where I left behind DNA evidence, and that was analyzed, would it be close enough to my brother’s to flag him as a potential relation and therefore potentially connect me to the crime? Are there other circumstances where it could (i.e. parent, child, or fraternal/identical twin on file)? ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [January 30, 2017, 11:11pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/2 "2017-01-30T23:11:07Z")
I believe they can determine family members from DNA. It’s probably enough of a match to get you to submit your own sample ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [January 30, 2017, 11:11pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/3 "2017-01-30T23:11:13Z")
Apparently. They just solved the [40-year-old murder](http://viveremilano.biz/2017/01/31/murder-of-righteous-brothers-bill-medleys-ex-wife-solved/) of one of the Righteous Brothers’ ex-wives using familial DNA. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [January 30, 2017, 11:16pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/4 "2017-01-30T23:16:39Z")
Yep. They would absolutely be able to tell that the DNA belonged to a close male relative of your brother. Also, aren’t you familiar with DNA paternity tests, the staple of court shows and daytime talk shows? The closer the genetic relationship, the more similar your genes are going to be. Even if the DNA samples are a[bit stale](https://www.google.com/#q=tutankhamun+akhenaten+dna). ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [January 30, 2017, 11:24pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/5 "2017-01-30T23:24:58Z")
Well that’s unfortunate. I wasn’t planning on committing any crimes anyway, but just knowing that I’ll never be able to pull off the perfect murder because my _sibling_ messed it up for me is kind of upsetting. ---
**Author:** ![AlsoNamedBort](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alsonamedbort/32/3213_2.png) [@AlsoNamedBort](https://boards.straightdope.com/u/AlsoNamedBort)\ **Post date:** [January 30, 2017, 11:30pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/6 "2017-01-30T23:30:40Z")
Note, it’s not done in every state > [@](#): > > Eight other states like Colorado, Wisconsin, Virginia, Michigan, Texas, Wyoming, Utah, Florida, have various protocol to use familial DNA. It is not available in New York, where Vetrano was murdered, due to privacy concerns. [http://www.insideedition.com/headlines/21345-dad-of-murdered-jogger-appeals-to-lawmakers-to-adopt-divisive-dna-match-technique-to-find](http://www.insideedition.com/headlines/21345-dad-of-murdered-jogger-appeals-to-lawmakers-to-adopt-divisive-dna-match-technique-to-find) ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [January 30, 2017, 11:32pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/7 "2017-01-30T23:32:07Z")
> [@Rigamarole](#): > > Well that’s unfortunate. I wasn’t planning on committing any crimes anyway, but just knowing that I’ll never be able to pull off the perfect murder because my _sibling_ messed it up for me is kind of upsetting. Just salt the crime scene with your brother’s DNA. There has got to some forensic principle that favors a precise hit over a near-hit, right? The most astute thing they could say is “\ was definitely there. There are also samples that are…” and then either “close to \, maybe a male relative”; “probably corrupted samples of \'s DNA, so disregard”; or “don’t matter, we have a precise match. Arrest \.” ---
**Author:** ![SpoilerVirgin](https://avatars.discourse-cdn.com/v4/letter/s/4491bb/32.png) [@SpoilerVirgin](https://boards.straightdope.com/u/SpoilerVirgin)\ **Post date:** [January 30, 2017, 11:49pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/8 "2017-01-30T23:49:00Z")
> [@gnoitall](#): > > Just salt the crime scene with your brother’s DNA. There has got to some forensic principle that favors a precise hit over a near-hit, right? The most astute thing they could say is “\ was definitely there. There are also samples that are…” and then either “close to \, maybe a male relative”; “probably corrupted samples of \'s DNA, so disregard”; or “don’t matter, we have a precise match. Arrest \.” Need to make sure that brother isn’t actually in prison at the time, and doesn’t have an airtight alibi. The usual T.V. procedural method is to leave brother a message telling him to meet someone at some weird out of the way or even nonexistent location, so he doesn’t have an alibi (but then there turns out to be a traffic camera he passes at a time that makes it clear that he couldn’t have gotten back fast enough to the commit the crime anyway). ---
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [January 31, 2017, 1:54am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/9 "2017-01-31T01:54:05Z")
Interesting you should ask. > **[The Daring DNA Hunt That Cracked France’s Gruesome Cold Case](https://www.thedailybeast.com/the-daring-dna-hunt-that-cracked-frances-gruesome-cold-case)** > > Thanks to American science and a determined French cop, a young woman whose burned corpse was found by a farmer 15 years ago may get justice. > [@](#): > > The persistent investigator took LaBerge’s advice. Those same rare markers from the unknown sample turned up in a man who was in prison for sexual assault. The case solidified when it turned out the inmate also had the same Y chromosome type, which identifies the male gene, as that found in the mystery DNA. When Pham-Hoai circled in on the family, he found the man did have a son named Greg Wiart, but Wiart was dead: killed just a year and a half after Elodie’s murder, when he ran his car into a beet truck. > > Finally, with this break in the investigation, French law enforcement was listening to the persistent Gendarme captain. To the dismay of Wiart’s family, a judge ordered for his body to be exhumed to obtain a tissue sample. > > “When Pham-Hoai called me, he was in tears,” LaBerge remembers. “He was over-the-moon excited to tell me there was a match ---
**Author:** ![sweepkick](https://avatars.discourse-cdn.com/v4/letter/s/87869e/32.png) [@sweepkick](https://boards.straightdope.com/u/sweepkick)\ **Post date:** [January 31, 2017, 4:43am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/10 "2017-01-31T04:43:45Z")
They got the BTK Killer using his daughter’s DNA. From [Wikipedia](https://en.wikipedia.org/wiki/Dennis_Rader): > [@](#): > > The police had strong circumstantial evidence against Rader, but they needed more direct evidence to detain him.[34] They obtained a warrant to test the DNA of a pap smear Rader’s daughter had taken at the Kansas State University medical clinic when she was a student. The DNA of the pap smear was processed by the Kansas Bureau of Investigation at their lab in Topeka and demonstrated a familial match to the DNA of the sample taken from victim Vicki Wegerle’s fingernails. This indicated that the killer was closely related to Rader’s daughter, and was the evidence the police needed to make an arrest.[35] ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [January 31, 2017, 5:26am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/11 "2017-01-31T05:26:50Z")
full sibling is going to be about 50% match to you. So is your father. So your uncles could be 25% match. it goes downhill quickly. First cousin, 12.5%. Not the Y is a special case. All males get their Y chromosome pretty much intact from their father. (They’ve used it to show that Jefferson’s slave had children by him… or possibly his brother or his father or his uncle…) A statistical match indicates male from same paternal source. To some extent, genes do change over time, so how much “drift” can indicate degrees of separation in historical timelines or further. (I.e. Native Americans split from remaining Siberians about 24,000 years ago.) ---
**Author:** ![PatrickLondon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/patricklondon/32/4422_2.png) [@PatrickLondon](https://boards.straightdope.com/u/PatrickLondon)\ **Post date:** [January 31, 2017, 8:35am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/12 "2017-01-31T08:35:36Z")
It’s certainly happened in the UK: > **[Killer convicted thanks to relative's DNA](https://www.newscientist.com/article/dn4908-killer-convicted-thanks-to-relatives-dna/)** > > The world's first conviction using "familial searching" to track a suspect via a relative's DNA is made in the UK ---
**Author:** ![si\_blakely](https://avatars.discourse-cdn.com/v4/letter/s/d9b06d/32.png) [@si\_blakely](https://boards.straightdope.com/u/si_blakely)\ **Post date:** [January 31, 2017, 9:35am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/13 "2017-01-31T09:35:09Z")
> [@PatrickLondon](#): > > It’s certainly happened in the UK: > > [https://www.newscientist.com/article/dn4908-killer-convicted-thanks-to-relatives-dna/](https://www.newscientist.com/article/dn4908-killer-convicted-thanks-to-relatives-dna/) I thought of that conviction. I saw the truck parked on the side of the M3 with a brick-shaped hole in the windshield the morning after as I drove to work, and was very pleased that the perpetrator was caught, many months later. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [January 31, 2017, 1:53pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/14 "2017-01-31T13:53:13Z")
Not a criminal case but a mystery woman’s family was [located](http://www.seattletimes.com/seattle-news/special-reports/my-god-thats-kimberly-online-sleuth-solves-perplexing-mystery-of-identity-thief-lori-ruff/) via a DNA match with a cousin on 23andMe. **FtGKid2** did the 23andMe thing and found a match that’s ~3rd cousin. Later an uncle also had it done and of course it turned up **FtGKid2**. No surprise there. There are several such commercial DNA databases now, as well as various police ones. Finding familial matches is getting more and more likely. If you are not guilty of something, you could still end up in serious trouble. If the police find someone in your family is a close-ish match to the DNA of a perp, they might decide you’re the closest in appearance to the suspect, etc. You get arrested, charged, etc. Eventually cleared via the DNA not being an exact match but by then you’ve burned through thousands of dollars in legal fees, lost your job, turned into a pariah within your community, etc. ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [February 3, 2017, 8:30am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/15 "2017-02-03T08:30:04Z")
> [@](#): > > It is not available in New York, where Vetrano was murdered, due to privacy concerns. But, but—they use it on _Law & Order: SVU_ every other week! :eek: ---
**Author:** ![robert\_columbia](https://avatars.discourse-cdn.com/v4/letter/r/e79b87/32.png) [@robert\_columbia](https://boards.straightdope.com/u/robert_columbia)\ **Post date:** [February 3, 2017, 1:35pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/16 "2017-02-03T13:35:02Z")
> [@md2000](#): > > …Not the Y is a special case. All males get their Y chromosome pretty much intact from their father. (They’ve used it to show that Jefferson’s slave had children by him… or possibly his brother or his father or his uncle…) A statistical match indicates male from same paternal source… The Y-chromosome is turning out to be very interesting in terms of tracing _distant_ relatives because of how slowly it mutates and the fact that it does not (normally, at least) recombine. [Here’s](http://www.dailymail.co.uk/news/article-2084692/Sarah-Yarborough-murder-Could-DNA-linked-17th-century-Mayflower-family-solve-1991-case.html) a case where the DNA of a wanted murderer in Washington State (1991 murder) has been paternally linked via the Y-chromosome to an early (1600’s) settler family in Massachusetts. Police now believe that the killer (whose exact identity is still unknown) is likely to have the last name Fuller. Henry Louis Gates, Jr., the African-American man who was famously arrested for burglary for trying to break into his own home, [has Y-chromosome type R-M222](http://scienceblogs.com/gnxp/2010/03/18/the-luck-of-the-irish/), which is associated with Irish and Scottish Gaelic ancestry. I also have this type, so this is a particular area of interest for me. ---
**Author:** ![Vicsage](https://avatars.discourse-cdn.com/v4/letter/v/e68b1a/32.png) [@Vicsage](https://boards.straightdope.com/u/Vicsage)\ **Post date:** [February 3, 2017, 3:02pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/17 "2017-02-03T15:02:49Z")
If you get a massive blood transfusion just before they test your blood, will that mess up the DNA test? ---
**Author:** ![Kelevra](https://avatars.discourse-cdn.com/v4/letter/k/97f17d/32.png) [@Kelevra](https://boards.straightdope.com/u/Kelevra)\ **Post date:** [February 3, 2017, 4:05pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/18 "2017-02-03T16:05:53Z")
> [@gnoitall](#): > > Just salt the crime scene with your brother’s DNA. There has got to some forensic principle that favors a precise hit over a near-hit, right? The most astute thing they could say is “\ was definitely there. There are also samples that are…” and then either “close to \, maybe a male relative”; “probably corrupted samples of \'s DNA, so disregard”; or “don’t matter, we have a precise match. Arrest \.” I vaguely recall seeing a sci-fi show where the perpetrators of a crime set off a “DNA bomb” to confuse any attempt at identifying them. I always wondered if that would work. If I decide to lead a life of crime my first order of business will be to raid the dumpsters of barbershops and mani/pedi stores! ---
**Author:** ![aruvqan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/aruvqan/32/2891_2.png) [@aruvqan](https://boards.straightdope.com/u/aruvqan)\ **Post date:** [February 4, 2017, 1:22am UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/19 "2017-02-04T01:22:20Z")
> [@Vicsage](#): > > If you get a massive blood transfusion just before they test your blood, will that mess up the DNA test? Now that is a hell of a good question! Me? I am screwed sort of. AB negative blood type, so as a fairly small % of adult females in the US share my blood type, even if all they can do is blood type without getting enough DNA I am enough at risk of being pined for a crime. I would have hated to have luminol’d my old house, we had a pair of dogs get into a fight in the living room, we were still finding random little visible blood spatters for almost 15 years [until it burnt down…] Though I really have to be peeved at the idiots who did a Lizzie Bordon documentary about 10 years ago. They luminol’d the area in the basement near the jakes [primitive toilet facility] and found washed out blood patches. ALl I could think of was 'a predominately female house population in an era with hand laundering everything, sharing a primitive toilet facility in an era when you used rags that needed to be hand washed out to deal with menstrual fluids … no shit you would find dilluted blood splashed around. Ever hand washed using a scrub board and hand wrung and hung up laundry before? Done a pitcher and pan ‘shower’ with menstrual fluid on your thighs? Hells bells, I have cleaned ‘blood drops’ off the bathroom walls and floors at home, and I _know_ I tried to be neat and tidy about things [I admit there was a bit of a learning curve in dealign with a diva cup…oops:o] If there is a menstruating woman there _will_ be blood evidence. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [February 23, 2017, 3:54pm UTC](https://boards.straightdope.com/t/if-a-close-relative-has-dna-on-file-can-that-potentially-compromise-you/778620/20 "2017-02-23T15:54:52Z")
Thought [this latest DNA identification story](https://qz.com/916728/dna-evidence-proves-a-maternal-dynasty-existed-in-north-america-1200-years-ago/) was worth a bump: a set of 14 1,200ish year old skeletons are DNA tested, found to all be from the same mitochondrial lineage, and that one pair was a mother and daughter and another were a grandmother and grandson.